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# Photonics

## IntroductionGeneral informationAccess profileOutput profileNumber of placesDuration and dedicationFees GrantsOrganizationAgreementsRegulations Access, admission and registrationAccess profileAccess requirementsAdmission and meritsPre-registration Training complementsEnrollmentAcademic calendar Monitoring and evaluation of the doctoral studentResearch planDAD tracking Formation activitiesDoctoral thesisPermanenceInternational mentionLearning resourcesDoctoral ThesesAuthorized for defenseIn public depositRepository of defended thesesAssociated publicationsResearch projectsTeaching staff and research groupsResearch groupsTeachersResearch projectsQualityIndicators

Photonics is the science that studies light and its generation, propagation, manipulation and interaction with matter. The discipline produces multidisciplinary technology with applications in communications, industry, nanotechnology, biology, medicine and other fields. In recent decades, photonics has given rise to a myriad of applications that have a positive impact on our lives, even at the most everyday level. Examples of photonic solutions to present-day challenges include modern fibre optics–based communications systems, optical diagnostic and therapeutic tools used in medicine, laser-based production methods, metrology and optical sensors, and photovoltaic energy.

.The doctoral programme in Photonics of the Universitat Politècnica de Catalunya (UPC) is delivered by the Institute of Photonic Sciences (ICFO) within the framework of the UPC Doctoral School. The ICFO is a research centre dedicated to the study of light sciences and technologies and has been recognised as a Severo Ochoa Centre of Excellence. Founded in 2002 by the Government of Catalonia and the UPC, the ICFO also hosts ambitious patronage programmes funded by the Cellex and Mir-Puig foundations of Barcelona. The Institute has a threefold mission: frontier research, knowledge and technology transfer, and postgraduate training, mainly at the doctoral level. The ICFO is currently one of the leading centres in the world in its field.

Theses are completed in the four research areas at the core of the doctoral programme in Photonics: biomedical photonics, quantum optics, nonlinear optics and nanophotonics. These four research areas focus primarily on photonic applications in healthcare, renewable energies and information technologies. Research is carried out within the framework of long-term programmes and medium-term projects in a range of fields, including quantum information technologies, advanced screens, nanophotonic devices, graphene photonics, remote sensors, solar cells, optoelectronics, integrated optics, ultrafast optics, super-resolution imaging techniques, and biomedical technologies for diagnosis and therapy.

Sewell, Robert

#### CONTACT

Natalia García Tusquellas
The Institute of Photonic Sciences (ICFO)
Av. Carl Friedrich Gauss, 3
08860 Castelldefels

Tel: (+34) 93 554 22 10

Programme website

# General information

### Access profile

The doctoral programme in Photonics is designed for students with outstanding academic records at the international level who wish to complete a doctoral project in a field related to photonics.

With respect to entrance qualifications, it should be noted that photonics is a very broad discipline and that the ICFO is made up of a number of research groups that work in the various branches of the photonic sciences. Accordingly, the doctoral programme in Photonics is open to applicants with a wide range of qualifications, including degrees in physics; electronic, electrical, materials and telecommunications engineering; mathematics, chemistry, biology, bioengineering and biophysics.

As for language skills, the ICFO is a research institute with a strongly international character and English is the language used for everyday communication. Students admitted to the doctoral programme in Photonics must therefore have a high level of written and spoken English.

As for career goals, the doctoral programme in Photonics admits both students who wish to pursue academic careers and those aiming to become future leaders in knowledge and technology transfer or R&D in the business environment.

When it comes to personal characteristics, we are looking for students with high potential, motivation and the drive to carry out a project of excellence at the highest international level.

### Output profile

Doctoral candidates who complete a doctoral degree will have acquired the following competencies, which are needed to carry out quality research (Royal Decree 99/2011, of 28 January, which regulates official doctoral studies):

a) A systematic understanding of the field of study and a mastery of the research skills and methods related to the field.
b) An ability to conceive, design or create, put into practice and adopt a substantial process of research or creation.
c) An ability to contribute to pushing back the frontiers of knowledge through original research.
d) A capacity for critical analysis and an ability to assess and summarise new and complex ideas.
e) An ability to communicate with the academic and scientific community and with society in general as regards their fields of knowledge in the manner and languages that are typical of the international scientific community to which they belong.
f) An ability to foster scientific, technological, social, artistic and cultural progress in academic and professional contexts within a knowledge-based society.

The award of a doctoral degree must equip the graduate for work in a variety of settings, especially those requiring creativity and innovation. Doctoral graduates must have at least acquired the personal skills needed to:

a) Develop in contexts in which there is little specific information.
b) Find the key questions that must be answered to solve a complex problem.
c) Design, create, develop and undertake original, innovative projects in their field.
d) Work as part of a team and independently in an international or multidisciplinary context.
e) Integrate knowledge, deal with complexity and make judgements with limited information.
f) Offer criticism on and intellectually defend solutions.

Finally, with respect to competencies, doctoral students must:
a) have acquired advanced knowledge at the frontier of their discipline and demonstrated, in the context of internationally recognised scientific research, a deep, detailed and well-grounded understanding of theoretical and practical issues and scientific methodology in one or more research fields;
b) have made an original and significant contribution to scientific research in their field of expertise that has been recognised as such by the international scientific community;
c) have demonstrated that they are capable of designing a research project that serves as a framework for carrying out a critical analysis and assessment of imprecise situations, in which they are able to apply their contributions, expertise and working method to synthesise new and complex ideas that yield a deeper knowledge of the research context in which they work;
d) have developed sufficient autonomy to set up, manage and lead innovative research teams and projects and scientific collaborations (both national and international) within their subject area, in multidisciplinary contexts and, where appropriate, with a substantial element of knowledge transfer;
e) have demonstrated that they are able to carry out their research activity in a socially responsible manner and with scientific integrity;
f) have demonstrated, within their specific scientific context, that they are able to make cultural, social or technological advances and promote innovation in all areas within a knowledge-based society;
g) have demonstrated that they are able to participate in scientific discussions at the international level in their field of expertise and disseminate the results of their research activity to audiences of all kinds.

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### Duration of studies and dedication regime

Duration
The maximum period of study for full-time doctoral studies is three years, counted from the date of admission to the programme to the date of submission of the doctoral thesis. The academic committee of the doctoral programme may authorise a doctoral candidate to pursue doctoral studies on a part-time basis. In this case, the maximum period of study is five years, counting from the date of admission to the programme to the date of submission of the doctoral thesis. For calculating these periods, the date of admission is considered to be the date of the first enrolment for tutorials, and the date of submission the moment in which the Doctoral School officially deposits the doctoral thesis.

For full-time doctoral candidates, the minimum period of study is two years, counted from the date of an applicant's admission to the programme until the date on which the doctoral thesis is deposited; for part-time doctoral candidates it is four years. When there are justified grounds for doing so, and the thesis supervisor and academic tutor have given their authorisation, doctoral candidates may request that the academic committee of their doctoral programme exempt them from the minimum period of study requirement.

The calculation of periods of study will not include periods of absence due to illness, pregnancy or any other reason provided for in the regulations in force. Students who find themselves in any of these circumstances must notify the academic committee of the doctoral programme, which, where appropriate, must inform the Doctoral School. Doctoral candidates may also temporarily withdraw from the programme for up to one year, and this period may be extended for an additional year. Doctoral candidates who wish to interrupt their studies must submit a justified request to the academic committee of the doctoral programme, which will decide whether or not to approve the request. Each programme will establish conditions for readmission to doctoral studies.

Extension
If full-time doctoral candidates have not applied to deposit their thesis by the end of the three-year period of study, the academic committee of the programme may authorise an extension of up to one year. In exceptional circumstances, a further one-year extension may be granted, subject to the conditions established by the corresponding doctoral programme. In the case of part-time doctoral candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

Dismissal from the doctoral programme
A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

### Enrollment aid

The ICFO and the professors involved in the doctoral programme are committed to ensuring that all doctoral students receive a grant and/or salary that allows them to work on their doctoral thesis full-time. The grants provided cover enrolment fees.

### Organization

COORDINATOR:
STRUCTURAL UNITS:
• Institute of Photonic Sciences (PROMOTORA)
Specific URL of the doctoral program:
http://phd.icfo.eu/

CONTACT:

Natalia García Tusquellas
The Institute of Photonic Sciences (ICFO)
Av. Carl Friedrich Gauss, 3
08860 Castelldefels

Tel: (+34) 93 554 22 10

### Agreements with other institutions

The ICFO has collaboration agreements in effect with a significant number of companies, including Leica Microsystems, Corning, Nikon-Izasa Grupo Sorigué, Accelerate Diagnostics, S.L., Fyla All-Fiber Ultrafast Lasers and GRAPHENEA. The Institute also participates in networks of excellence (Euro-BioImaging, Laserlab Europe, Corbel, etc.) and coordinates various Graphene Flagship and Quantum Flagship projects under the EU's Horizon 2020 Programme.

### Access profile

The doctoral programme in Photonics is designed for students with outstanding academic records at the international level who wish to complete a doctoral project in a field related to photonics.

With respect to entrance qualifications, it should be noted that photonics is a very broad discipline and that the ICFO is made up of a number of research groups that work in the various branches of the photonic sciences. Accordingly, the doctoral programme in Photonics is open to applicants with a wide range of qualifications, including degrees in physics; electronic, electrical, materials and telecommunications engineering; mathematics, chemistry, biology, bioengineering and biophysics.

As for language skills, the ICFO is a research institute with a strongly international character and English is the language used for everyday communication. Students admitted to the doctoral programme in Photonics must therefore have a high level of written and spoken English.

As for career goals, the doctoral programme in Photonics admits both students who wish to pursue academic careers and those aiming to become future leaders in knowledge and technology transfer or R&D in the business environment.

When it comes to personal characteristics, we are looking for students with high potential, motivation and the drive to carry out a project of excellence at the highest international level.

### Access requirements

Applicants must hold a Spanish bachelor’s degree or equivalent and a Spanish master’s degree or equivalent, provided they have completed a minimum of 300 ECTS credits on the two degrees (Royal Decree 43/2015, of 2 February)

In addition, the following may apply:

• Holders of an official degree awarded by a university in Spain or any other country in the European Higher Education Area, pursuant to the provisions of Article 16 of Royal Decree 1393/2007, of 29 October, which establishes official university course regulations, who have completed a minimum of 300 ECTS credits on official university degrees, of which at least 60 must be at the master's degree level.
• Holders of an official Spanish bachelor’s degree comprising at least 300 credits, as provided for by EU regulations. Holder of degrees of this kind must complete bridging courses unless the curriculum of the bachelor’s degree in question included research training credits equivalent in value to those which would be earned on a master's degree.
• Holders of an official university qualification who, having passed the entrance examination for specialised medical training, have completed at least two years of a training course leading to an official degree in a health-sciences specialisation.
• Holders of a degree issued under a foreign education system. In these cases, homologation is not required, but the UPC must verify that the degree certifies a level of training equivalent to an official Spanish master's degree and qualifies the holder for admission to doctoral studies in the country where it was issued. Admission on this basis does not imply homologation of the foreign degree or its recognition for any purpose other than admission to doctoral studies.
• Holders of a Spanish doctoral qualification issued under previous university regulations.
• Note 1: Doctoral studies entrance regulations for holders of an undergraduate degree awarded before the introduction of the EHEA (CG 47/02 2014)

Note 2: Governing Council Decision 64/2014, which approves the procedure and criteria for assessing the fulfilment of academic admission requirements for doctoral studies by holders of non-homologated foreign degrees (CG 25/03 2014)

### Admission criteria and merits assessment

Applications for admission to the doctoral programme in Photonics must be submitted through the website http://jobs.icfo.eu/, to which interested students are directed. Detailed information on specific vacancies available for doctoral students at any given time in each of the ICFO's research groups is published on this web page.

The following admission requirements are assessed on a yes/no basis and must be met to undertake the selection process:

• High level of English.
• High level of academic performance (GPA).
• Motivation to pursue doctoral studies in one of the fields of the doctoral programme.

In the first stage of the selection process, carried out by the admission body for the Photonics programme, requirements are assessed based on documents submitted in the application process, which are standardised to ensure that the assessment process is fair and unbiased. Accepted applications are assessed based on the following criteria, which carry equal weight:

• Previous research and cross-cutting experience (25%).

• Academic excellence and other achievements (25%).
• Statement of research interests (25%).
• Quality of references (25%).

In the second stage of the selection process, carried out by a selection committee appointed specifically for the call, assessment is based on the written proposals submitted by applicants (if applicable), their performance in an interview, and their answers to questions from the selection committee. The following criteria are considered and carry equal weight:

• Presentation of the research project (33%).
• Motivation to pursue doctoral studies in the chosen field and scientific interests (33%).
• Competencies and skills with respect to communication, independence, initiative and teamwork (33%).

Each of these points is assessed by assigning a score from 0 to 5 based on standardised scales. These scores are then combined (with equal weighting) to obtain the final result, which will determine the ranking of applicants.

Finally, measures are taken to ensure that the principles of transparency, efficiency and international compatibility set out in the European Charter for Researchers and the European Code of Conduct for the Recruitment of Researchers are followed throughout the admission process for the doctoral programme in Photonics. The process will also be free of any discrimination based on gender or nationality.

### Training complements

Students who hold one of the following UPC master’s degrees, which are linked to the doctoral programme, will not be required to complete bridging courses: Erasmus Mundus master's degree in Photonics; master's degree in Photonics Engineering, Nanophotonics and Biophotonics; master's degree in Engineering Physics; and master's degree in Quantum Science and Technology.

Neither will students who have completed a master's degree in photonics or physics from another university be required to complete bridging courses.

In the case of students who have completed a master's degree in another field – such as a master's degree in biomedical sciences or a multidisciplinary master's degree in experimental sciences – the applicant’s academic record and the project they propose to work on will be assessed, and the academic committee will determine on a case-by-case basis whether specific bridging courses must be completed. If the academic committee so determines, these students will be required to take one of the following subjects as a bridging course:

• Introduction to Photonics. Optics and Lasers (5 ECTS credits), from the master’s degree in Photonics
• Applied Photonics (5 ECTS credits), from the master's degree in Enabling Technologies for the Food and Bioprocessing Industry.

### Enrolment period for new doctoral students

Enrolment is open year round, subject to the calendar established by the Doctoral School.

In September.

# Monitoring and evaluation of the doctoral student

### Procedure for the preparation and defense of the research plan

Doctoral candidates must submit a research plan, which will be included in their doctoral student activity report, before the end of the first year. The plan may be improved over the course of the doctoral degree. It must be endorsed by the tutor and the supervisor, and it must include the method that is to be followed and the aims of the research.

At least one of these annual assessments will include a public presentation and defence of the research plan and work done before a committee composed of three doctoral degree holders, which will be conducted in the manner determined by each academic committee. The examination committee awards a Pass or Fail mark. A Pass mark is a prerequisite for continuing on the doctoral programme. Doctoral candidates awarded a Fail mark must submit a new research plan for assessment by the academic committee of the doctoral programme within six months.

The committee assesses the research plan every year, in addition to all of the other activities in the doctoral student activity report. Doctoral candidates who are awarded two consecutive Fail marks for the research plan will be obliged to definitely withdraw from the programme.

If they change the subject of their thesis, they must submit a new research plan.

### Formation activities

The doctoral programme in Photonics does not specify any minimum requirements with respect to number of papers published, conferences attended, or other activities. However, the academic committee for the programme will seek to ensure that each thesis meets the highest international standards before it is accepted for oral defence.

The training activities that make up the programme (including details of their duration and whether they are compulsory or optional) are listed below.

Mobility, 3 months (optional)
Preparation and initial defence of research plan, 50 hours (compulsory)
Training in information skills, 1.5 hours (optional)
Research Methodology, 12 hours (optional)
Innovation and Creativity, 8 hours (optional)
Language and Communication Skills, 18 hours (optional)
Scientific seminars, 25 hours/year (optional)
ICONS seminars, 40 hours/year (optional)
Coffee sessions with prominent researchers, 2 hours/year (optional)
Programme-specific workshops, 1 day/year (optional)
Publications, 50 hours (compulsory)
PhD lectures, 65 hours/year (optional)
Outreach activities, 18 hours (optional)
Training in technical skills, 5 hours for each technique (optional)
Effective Oral Presentations, 10 hours (optional)
Introduction to Patent Engineering and Management, 7.5 hours (optional)
Language courses, 40 hours (Spanish, Catalan and English; optional)
Research Integrity, 3 hours (compulsory)
Career Development, 10 hours (optional)
Resilience and Well-Being, 6 hours (optional)
Essential Transferable Skills for Early Career Researchers, 12 hours (optional).

### Procedure for assignment of tutor and thesis director

The academic committee of the doctoral programme assigns a thesis supervisor to each doctoral candidate when they are admitted or enrol for the first time, taking account of the thesis supervision commitment referred to in the admission decision.

The thesis supervisor will ensure that training activities carried out by the doctoral candidate are coherent and suitable, and that the topic of the candidate’s doctoral thesis will have an impact and make a novel contribution to knowledge in the relevant field. The thesis supervisor will also guide the doctoral candidate in planning the thesis and, if necessary, tailoring it to any other projects or activities undertaken. The thesis supervisor will generally be a UPC professor or researcher who holds a doctoral degree and has documented research experience. This includes PhD-holding staff at associated schools (as determined by the Governing Council) and UPC-affiliated research institutes (in accordance with corresponding collaboration and affiliation agreements). When thesis supervisors are UPC staff members, they also act as the doctoral candidate’s tutor.

PhD holders who do not meet these criteria (as a result of their contractual relationship or the nature of the institution to which they are attached) must be approved by the UPC Doctoral School's Standing Committee in order to participate in a doctoral programme as researchers with documented research experience.

The academic committee of the doctoral programme may approve the appointment of a PhD-holding expert who is not a UPC staff member as a candidate’s thesis supervisor. In such cases, the prior authorisation of the UPC Doctoral School's Standing Committee is required. A UPC staff member who holds a doctoral degree and has documented research experience must also be proposed to act as a co-supervisor, or as the doctoral candidate’s tutor if one has not been assigned.

A thesis supervisor may step down from this role if there are justified reasons (recognised as valid by the committee) for doing so. If this occurs, the academic committee of the doctoral programme will assign the doctoral candidate a new thesis supervisor.

Provided there are justified reasons for doing so, and after hearing any relevant input from the doctoral candidate, the academic committee of the doctoral programme may assign a new thesis supervisor at any time during the period of doctoral study.

If there are academic reasons for doing so (an interdisciplinary topic, joint or international programmes, etc.) and the academic committee of the programme gives its approval, an additional thesis supervisor may be assigned. Supervisors and co-supervisors have the same responsibilities and academic recognition.

The maximum number of supervisors of a doctoral thesis is two: a supervisor and a co-supervisor.

For theses carried out under a cotutelle agreement or as part of an Industrial Doctorate, if necessary and if the agreement foresees it this maximum number of supervisors may not apply. This notwithstanding, the maximum number of supervisors belonging to the UPC is two.

### Permanence

The academic committee of the programme may authorise an extension of up to one year for full-time doctoral candidates who have not applied to deposit their thesis by the end of the three-year period of study, in the terms outlined in the Academic Regulations for Doctoral Studies of the Universitat Politècnica de Catalunya. In the case of part-time candidates, an extension of two years may be authorised. In both cases, in exceptional circumstances a further one-year extension may be granted by the Doctoral School's Standing Committee, upon the submission of a reasoned application by the academic committee of the doctoral programme.

A doctoral candidate may be dismissed from a doctoral programme for the following reasons:

• The doctoral candidate submitting a justified application to withdraw from the programme.
• The maximum period of study and of extensions thereof ending.
• The doctoral candidate not having enrolled every academic year (unless he or she has been authorised to temporarily withdraw).
• The doctoral candidate failing two consecutive assessments.
• The doctoral candidate having disciplinary proceedings filed against him or her that rule that he or she must be dismissed from the UPC.

Dismissal from the programme implies that doctoral candidates cannot continue studying at the UPC and the closing of their academic record. This notwithstanding, they may apply to the academic committee of the programme for readmission and the committee must reevaluate them in accordance with the criteria established in the regulations.

### International Mention

The doctoral degree certificate may include International Doctorate mention. In this case, the doctoral candidate must meet the following requirements:

a) During the period of study leading to the award of the doctoral degree, the doctoral candidate must have spent at least three months at a respected higher education institution or research centre outside Spain to complete courses or do research work. The stays and activities carried out must be endorsed by the thesis supervisor and authorised by the academic committee of the programme. The candidate must provide a certifying document issued by the person responsible for the research group of the body or bodies where the stay or activity was completed. This information will be added to the doctoral student’s activity report.
b) Part of the thesis (at least the summary and conclusions) must be written and presented in one of the languages commonly used for science communication in the relevant field of knowledge, which must not be an official language of Spain. This rule does not apply to stays and reports in Spanish or to experts from Spanish-speaking countries.
c) At least two PhD-holding experts belonging to a higher education institution or research centre outside Spain must have issued officially certified reports on the thesis.
d) The thesis examination committee must have included at least one PhD-holding expert from a higher education or research institution outside Spain who was not responsible for the candidate’s stay abroad (point a) above).
e) The thesis defence must have taken place on UPC premises or, in the case of joint programmes, at the location specified in the collaboration agreement.

# Learning resources

In addition to the support units and services available at the UPC, the ICFO administration team is made up of staff with a high level of specialisation in various fields who provide specific and accessible assistance to students of the doctoral programme in Photonics. Specifically, the ICFO offers the following services and facilities:

• Human Resources and Education Unit: academic and hiring procedures, permits for foreign nationals, accommodation-related matters, predoctoral grants for doctoral studies, and mobility grants for doctoral students.
• Knowledge and Technology Transfer Unit: https://www.icfo.eu/lang/industry
• ICFO Projects Unit: responsible for seeking funding opportunities, advising researchers on preparation of proposals, and processing applications.

Doctoral students in the Photonics programme also have access to the NanoFabrication Lab, the Super-Resolution Light Microscopy and Nanoscopy Research Facility, the Advanced Engineering Lab, the Biology Lab, the Chemistry Lab and the Post-Processing Lab: https://www.icfo.eu/lang/research/facilities

# Doctoral Theses

## List of authorized thesis for defense

• ARGÜELLO LUENGO, JAVIER: Synthetic quantum matter using atoms and light
Author: ARGÜELLO LUENGO, JAVIER
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 09/09/2022
Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
Thesis director: CHANG, DARRICK | GONZALEZ TUDELA, ALEJANDRO
Committee:
PRESIDENT: LEWENSTEIN, MACIEJ
SECRETARI: PORRAS TORRE, DIEGO
VOCAL: FEIST, JOHANNES MAXIMILIAN
Thesis abstract: Atomic and optical physics are two fields closely connected by a shared range of energy scales, and the interactions between them. Atoms represent the most fundamental components of matter, and interactions with electromagnetic fields are responsible for many properties used to characterize a material, like the emission and absorption of radiation by these systems. Over the last decades, this has allowed us to use light as a tool to access and manipulate the internal states of atomic systems. Such a quantum control has transformed atoms into one of the preferred platforms to explore fundamental science, including applications in quantum information, quantum metrology or, more recently, the realization of synthetic materials where light can induceinteractions that would be difficult to find intrinsically in real materials.In the first part of this Thesis, we show how single atoms coupled to a cavity field can offer unique opportunities as quantum optomechanical devices because of their small mass and strong interaction with light. In particular, we focus on the "single-photon strong coupling" regime, where motional displacements on the order of the zero-point uncertainty are sufficient to shift the cavityresonance frequency by more than its linewidth. By coupling atomic motion to the narrow cavity-dressed atomic resonance, we theoretically observe that the scattering properties of single photons can become highly entangled with the atomic wavefunction, even if the cavity linewidth is large. This leads to a per-photon motional heating that is significantly larger than the single-photonrecoil energy, as well as mechanically-induced oscillations that could be observed in the correlations of state-of-the-art cavity systems.In the second part of the Thesis, we investigate how synthetic materials built using light can be harnessed as quantum simulators, defeating the limitations that classical computers face in the exploration of quantum phenomena. We particularly focus on ultracold atomic mixtures trapped in optical lattices, where atom-mediated long-range interactions can provide an enabling tool in the simulation of relevant problems in condensed matter or quantum chemistry.First, we show that fermionic atoms in an ultracold gas can act as a mediator, giving rise to effective long-range RKKY interactions among other neutral atoms trapped in an optical lattice. We further propose several experimental knobs to tune theseinteractions, which are characterized by the density and dimensionality of the gas and are accessible in current experimental platforms. We also show that these knobs open up the exploration of new frustrated regimes where symmetry-protectedtopological phases and chiral spin liquids emerge.Second, we introduce a set of experimental schemes where long-range interactions are mediated by an additional bosonic species trapped in a commensurate optical lattice, both in 2D and 3D. In particular, we show that the interplay with cavity QED can lead to effective Coulomb-like repulsion, which opens the door to the analog simulation of quantum chemistry problems usingultracold fermionic atoms as simulated electrons. Apart from explaining the emergent mechanism, we provide operational conditions for the simulator, benchmark it with simple atoms and molecules, and analyze how the continuous limit is approachedfor increasing optical lattice sizes. Finally, we compare our results with those of the continuum limit, where conventional quantum chemistry methods can be evaluated and tested.In summary, our results show connections between different areas of theoretical and experimental physics where light-matter interaction can play a dominant role, and suggest how this can be harnessed to further advance our understanding of stronglycorrelated quantum matter.
• BAREZA, NESTOR: Mid-Infrared Surface Sensing Based on Two-Dimensional Materials
Author: BAREZA, NESTOR
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 22/07/2022
Thesis director: PRUNERI, VALERIO | PAULILLO, BRUNO
Committee:
SECRETARI: GRIGORENKO, ALEXANDER NIKOLAEVICH
VOCAL: MERKOÇI, ARBEN
Thesis abstract: Mid-infrared (mid-IR) spectroscopy in the wavelength region between 2 and 20 µm is a powerful technique to identify vibrational absorption signatures of molecules, finding in this way extensive applications in healthcare, environmental monitoring, and chemical analysis. Enhanced IR light-molecules interactions can be achieved by exploiting nanostructured surfaces supporting polaritons ¿ hybrid excitations of light and dipolar elements of matter. Recently, polaritons of two-dimensional van der Waals (2D-vdW) materials unveiled a vibrant playground for mid-IR spectroscopy as they possess remarkable properties such as light trapping at deep nanoscale. This dissertation aims to investigate 2D-vdW materials for technological sensing applications. Hence, we explore the mid-IR sensing performance of nanostructures of widely studied 2D-vdW crystals: graphene (the pioneering vdW material with tunable plasmon polaritons) and hexagonal boron nitride (hBN, sustaining ultralow-loss phonon polaritons). Relevant functionalization layers, such as polymer adsorber and antibodies, are combined with the 2D-vdW nanostructures to create gas and for bio-molecular sensors, respectively.Here, we present three main experimental works of 2D-vdW-based mid-IR molecular sensing. First, we investigate the CO2 detection using graphene nanoribbons functionalized with ultrathin CO2-chemisorbing polyethylenimine (PEI). The localized surface plasmon resonance (LSPR) of graphene is modulated by varying CO2 gas concentration, whose substantial shifts are influenced by the reversible PEI-induced doping of graphene. Second, we examine the phonon-enhanced CO2 detection of hBN nanoresonators functionalized with thin PEI layer. The phonon-polariton resonance is modulated by varying CO2 levels with high signal-to-noise ratio signals. Third, we present a quantitative bioassay by transducing different vitamin B12 target concentrations into LSPR shifts of bio-functionalized graphene nanostructures (subsequent addition of pyrene linkers and recombinant anti-vB12 antibody fragments). Additionally, we observed the same result-trends for the same bioassay using graphene nanostructures fabricated both by small-scale (i.e., electron beam lithography) and large-scale (i.e., nanoimprint lithography) methods.Our proof-of-concept mid-IR sensing experiments show quantitative results for the detection of gas and biomarker with functionalized 2D-vdW nanostructures. The opportunity of combining the mid-IR spectroscopy with industrially large-scale 2D-vdW nanostructures (e.g., nanoimprinted GNH in this dissertation) would enable cost-effective technologies in future developments. This dissertation contributes to the field of 2D-vdW-based mid-IR spectroscopic sensors towards exploring novel designs and improved sensitivity, which eventually could lower the limit of detection for molecular analytes in various applications.
• DE ROQUE FERNANDEZ, PABLO MANUEL: Contributions to nanophotonics: linear, nonlinear and quantum phenomena
Author: DE ROQUE FERNANDEZ, PABLO MANUEL
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 06/04/2022
Thesis director: VAN HULST, NIEK
Committee:
PRESIDENT: QUIDANT, ROMAIN
VOCAL: AIZPURUA IRIAZABAL, JAVIER
Thesis abstract: Nanophotonics can be defined as the science and technology studying the control optical fields at the nanoscale and their interaction with matter. In order to spatially control such fields we would need structures with characteristic dimensions of the order of the wavelength, bringing us to the nanoscale. A way to control optical fields at this scale is the use of nanoantennas, optical equivalent of radio-antennas. They provide efficient interfaces between near-fields generated by light sources and radiative channels. After a brief Introduction, Chapter 2 describes interaction between single photon emitters and nanoantennas. We start the chapter introducing a method to numerically simulate the interaction. A key concept to solving Maxwell equations is that of the Green function. I show how this function relates to the emission rate of optical emitters in a nanophotonic environment. I then describe an our efforts to build a lifetime-imaging near-field scanning optical microscope. Using this rig we are able to measure changes changes in the emission rate of single emitters that interact with resonant optical antennas. A complementary way to control optical field in the nanoscale is using dielectric confinement. Chapter 3 introduces hybrid structures combining nanoantennas and dielectric waveguides. I generalize the Green function formalism introduced in Chapter 2, and show how this is related to the energy transfer rate between a donor and an acceptor. I use this numerical method to calculate the energy transfer rate in a hybrid structure. An increase of orders of magnitude is found at distances of the order of the wavelengths of the transferred photons. This chapter finishes by discussing the role that the local density of optical states has on the energy transfer efficiency.Nanoantennas increase near-field by orders of magnitude. In these conditions, nonlinear optical effects start to play a role. Chapter 4 is devoted to these nonlinear interactions mediated by nanoantennas. I explore nonlinear interactions in resonant nanoantennas, in particular SHG. First I introduce a method to numerically compute the contributions to SHG generated by the metal in nanoantennas. Both surface and bulk contributions to SHG are considered. I use the numerical method to show that narrowings within the antenna shape are sources of increased SHG. The increase in SHG is attributed to increase of the local field gradients, that increase to the bulk contribution to SHG. We numerically validate our results by performing SHG measurements at the single resonant antenna level.Optical fields are functions of space, but also of time. The development of broadband femtosecond lasers and pulse shaping techniques allows control of optical field down to the femtosecond timescale. Chapter 5 explores the control of optical fields in time. Using phase shaping methods we optimize the two-photon absorption process in single QDs. I introduce a new optimization algorithm, that allows us to perform the optimization using as feedback signal the luminesce from single QDs. We then compare our results with standard phase shaping techniques.Based on their success to effectively control all kinds of optical fields, plasmon supporting nanoantennas are being actively researched in the field of quantum optics. In Chapter 6 I describe a quantum eraser experiment mediated by structures supporting surface plasmon resonances. I first explain the details and subtleties of a quantum eraser experiment. I then detail our efforts to reproduce previously reported results about how to fabricate elliptical bullseye antennas behaving as quarter waveplates. Quarter waveplates are a required part for the quantum eraser effect to take place. An additional key component of our experiment is a bright, state-of-the-art entangle polarization entangle photon source that is described at length. We then perform a quantum eraser experiment mediated by plasmons.
• GRAVA, STEFANO: Novel quantum interactions between light and dense atomic media
Author: GRAVA, STEFANO
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 07/09/2022
Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
Thesis director: CHANG, DARRICK
Committee:
PRESIDENT: DE RIEDMATTEN, HUGUES
SECRETARI: BARREDO GONZALEZ, DANIEL
VOCAL: FERRIER-BARBUT, IGOR JULES
Thesis abstract: The interface between light and cold atomic ensembles is a fundamental platform to unravel the quantum world and develop quantum technological applications. Its success relies on the simple idea that the efficiency of such an interface can be collectively enhanced by the use of many atoms. While the interaction between its building blocks, a single photon, and a single atom, is theoretically and experimentally understood, instead, the interaction between light and a macroscopic ensemble of motionless atoms is generically a complex system featuring multiple scattering and many-body dipole interactions. To avoid the complexity, typical theories of atom-light interactions treat the atomic medium as smooth. However, it is well-known that microscopic optical effects driven by atomic granularity can lead to important effects, especially in dense media. These phenomena and their consequences on the performance of applications are not completely understood. To take them into account exactly, Chapter 1 introduces a ``spin model'' for light-matter interaction. The rest of the thesis is then divided into three chapters, which push forward our understanding of the interaction of light with dense atomic media.In Chapter 2 it is argued that because of the overwhelming collective macroscopic response an ensemble can exhibit (well captured by the standard theory), many microscopically-driven effects that have been predicted, have also been challenging to observe so far. An essential step is thus to suppress the macroscopic light propagation, so as to allow the microscopic correlations to build up and to be analyzed in a background-free fashion. To solve this issue, a technique to suppress the macroscopic optical dynamics in free space, which allows to precisely investigate many-body aspects of light-matter interaction, will be presented and demonstrated. In particular, we unravel and precisely characterize a microscopic, density-dependent dipolar dephasing effect that generally limits the lifetime of the optical spin-wave order in ensemble-based atom-light interfaces. In Chapter 3 we will go beyond the short-time and dilute limits considered previously, to develop a comprehensive theory of dephasing dynamics for arbitrary times and atomic densities. In particular, our non-perturbative approach is based on the strong-disorder renormalization group (RG), in order to quantitatively predict the dominant role that near-field optical interactions between nearby neighbors have in driving the dephasing process. This theory also enables one to capture the key features of the many-atom dephasing dynamics in terms of an effective single-atom model. These results should shed light on the limits imposed by near-field interactions on quantum optical phenomena in dense atomic media, and illustrate the promise of strong disorder RG as a method of dealing with complex microscopic optical phenomena in such systems.Chapter 4 tries to answer the question of why ordinary materials exhibit a refractive index of order unity and if the answer can come from an electro-dynamical argument. While textbook theories predict nonphysical values when extrapolated to densities of solids, here, we will evaluate the exact linear optical response of a three-dimensional lattice of two-level atoms, first from the band structure and then from a direct numerical simulation. Interestingly, when multiple scattering of light is exactly taken into account, as a result of perfect interference, it is found that an ideal unity-filled array of atoms can have a refractive index that grows with the density and is furthermore real. This implies that a saturation mechanism for the index should come from the quantum chemistry interactions that arise in real materials. Whether saturation could be circumvented, could lead to novel optical materials with transformative technological potential.
• HSIEH, CHUNG YUN: Resource Theories of Quantum Dynamics
Author: HSIEH, CHUNG YUN
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 12/09/2022
Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
Thesis director: ACÍN DAL MASCHIO, ANTONIO | LOSTAGLIO, MATTEO
Committee:
PRESIDENT: LEWENSTEIN, MACIEJ
SECRETARI: SKRZYPCZYK, PAUL ALAN
VOCAL: JENNINGS, DAVID
• JIMÉNEZ MACHADO, GERARD: Fundamentals of nonlinear interferometers and its use for optical coherence tomography
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 20/09/2022
Thesis director: PEREZ TORRES, JUAN
Committee:
PRESIDENT: PRUNERI, VALERIO
SECRETARI: ALONSO GONZALEZ, MIGUEL ANGEL
VOCAL: GRÄFE, MARKUS
Thesis abstract: This thesis, mostly experimental, is based on two fundamental pillars: nonlinear interferometers and Optical Coherence Tomography (OCT). Nonlinear interferometers are a class of interferometers that exhibit nonclassical phenomena brought on by nonlinear elements, such as optical parametric amplifiers and parametric down-conversion (PDC) nonlinear crystals. OCT is a non-invasive imaging technique that allows to obtain images with high axial and cross-sectional resolution of a wide variety of samples.The first novel contribution of this thesis is an experimental scheme that combines the two ideas: an OCT scheme based on a nonlinear interferometer. In these new approach the reflectivity of the sample translates in a loss of first-order coherence between two beams, that is the variable that is measured. In addition, it allows probing the sample with a wavelength different from the one that is measured. In this way, the penetration depth in the sample can be enhanced using longer wavelengths while using light at the optimal wavelength for detection.We present and implement two different experimental configurations. The first is a nonlinear interferometer based on induced coherence, or Mandel-type interferometer, that works in the low parametric gain regime of parametric down-conversion (PDC). The results presented here are a proof-of-concept, that can potentially offer new applications for OCT, but that are not meant to substitute traditional OCT systems. The second OCT scheme overcomes some of the limitations of the first scheme discussed above. It is an SU(1,1), or Yurke-type interferometer, that operates in the high parametric gain regime of parametric down-conversion. In addition to taking advantage of the salutary features of this new approach, it also enables obtaining values of power and axial resolution comparable to those of conventional OCT.The second novel contribution of this thesis is related to fundamental aspects at the heart of nonlinear interferometers. We discuss two experiments that study two important concepts behind the idea of induced coherence: quantum distinguishability and parametric amplification (stimulated emission). In the first experiment we propose a new experimental measure of quantum distinguishability and derive a complementarity relation between distinguishability and first-order coherence. In the second experiment, we contribute to the ongoing debate about the true role of quantum distinguishability and stimulated emission in explaining the induced coherence effect. Finally, we put forward theoretically a new scheme to retrieve transverse spatial information of a sample using a nonlinear interferometer, based on projecting the outgoing photons in selected spatial modes. We call this new proposal spatial spectroscopy, and it does not require a physical mechanical scan of the sample. We demonstrate the feasibility of the technique with a simple example. This last contribution constitutes a future proposal to be carried out with nonlinear interferometers, evidencing their great versatility and potential applications in new areas.
• KOTTMANN, KORBINIAN GEBHARD: Investigating Quantum Many-Body Systems with Tensor Networks, Machine Learning and Quantum Computers
Author: KOTTMANN, KORBINIAN GEBHARD
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 12/09/2022
Reading place: ICFO ¿ The Institute of Photonic Sciences - Campus Baix Llobregat - Av.Carl Friedrich Gauss, 3 08860 Castelldefels (Barcelona) - SPAIN
Thesis director: ACÍN DAL MASCHIO, ANTONIO | LEWENSTEIN, MACIEJ
Committee:
PRESIDENT: CHANG, DARRICK
SECRETARI: GREPLOVA, ELISKA
VOCAL: MARQUARDT, FLORIAN KAI
Thesis abstract: We perform quantum simulation on classical and quantum computers and set up a machine learning framework in which we can map out phase diagrams of known and unknown quantum many-body systems in an unsupervised fashion.The classical simulations are done with state-of-the-art tensor network methods in one and two spatial dimensions. For one dimensional systems, we utilize matrix product states (MPS) that have many practical advantages and can be optimized using the efficient density matrix renormalization group (DMRG) algorithm. The data for two dimensional systems is obtained from entangled projected pair states (PEPS) optimized via imaginary time evolution.Data in form of observables, entanglement spectra, or parts of the state vectors from these simulations, is then fed into a deep learning (DL) pipeline where we perform anomaly detection to map out the phase diagram.We extend this notion to quantum computers and introduce quantum variational anomaly detection. Here, we first simulate the ground state and then process it in a quantum machine learning (QML) manner. Both simulation and QML routines are performed on the same device, which we demonstrate both in classical simulation and on a physical quantum computer hosted by IBM.
• LAGO RIVERA, DARÍO: Remote distribution of quantum states assisted by multimode quantum memories
Author: LAGO RIVERA, DARÍO
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 12/09/2022
Thesis director: DE RIEDMATTEN, HUGUES
Committee:
PRESIDENT: PRUNERI, VALERIO
SECRETARI: HANSON, RONALD
VOCAL: AFZELIUS, MIKAEL
Thesis abstract: The future quantum Internet will allow the transfer of quantum states between remote locations. However, bridging large distances is a challenging task due to losses in optical fibres. A promising approach to reach continental distances is based on quantum repeaters, where quantum entanglement is created and distributed between distant quantum memories in a heralded fashion. Such a heralding signal should be compatible with the already deployed telecommunication infrastructure, i.e. it should consist of quantum states of light in the telecommunication regime travelling through optical fibres. On top of this, a multiplexed operation will largely reduce the entanglement generation time. The specific approach followed in this thesis consists of a hybrid system that combines sources of telecom heralded single photons and multimode solid-state quantum memories based on rare-earth doped crystals.The objective of this thesis is the distribution of quantum states along remote distances, either by storing one qubit in one quantum memory for long enough while the heralding photon travels through a telecom fibre, by teleporting an arbitrary qubit onto a distant matter qubit or by creating entanglement between remote quantum memories. Thanks to the intrinsic temporal multimodality of our system, the repetition rate of these experiments is decoupled from the distance being bridged. The core of my efforts consisted on building and operating telecom heralded single photon sources based on cavity enhanced spontaneous parametric down conversion (cSPDC). I was also involved on conceiving and implementing several enabling technologies to allow for the creation, distribution and verification of quantum states.In a first project it was possible to generate energy-time entangled photon pairs by increasing the coherence time of the laser used to pump the cSPDC source. We then stored one of the photons for up to 47.7us in a spin wave Praseodymium doped quantum memory with on-demand read out. The entanglement between the telecom photon and the stored photon was successfully verified in all the explored scenarios using the Franson scheme. For this purpose, I built and stabilized a fibre-based unbalanced Mach-Zehnder interferometer with a length difference between arms of 85m.In a second experiment we performed multiplexed quantum teleportation from the telecom photon to the solid-state memory. We took advantage of the telecom wavelength featured by one of the energy-time entangled qubits and we sent it through a 1km long optical fibre. After travelling through that distance it was jointly measured with a second qubit. The state of that second qubit was then teleported onto the quantum memory that was initially storing the second entangled qubit. The storage time was enough to allow for further processing of the teleported state, which consisted of a unitary transformation based on the result of the remote joint measurement.Finally, in a third experiment we generated telecom heralded entanglement between remote solid-state multimode quantum memories. I first worked on the indistinguishability of the photon pairs produced by two cSPDC sources. I then mixed the generated telecom qubits in a beam splitter (BS) such that a detection event after this BS heralded the creation of entanglement between the two quantum memories in the photon number basis. This way of creating entanglement, together with its verification, is sensitive to the relative phase of the qubits interfering at the BSs. Along these lines, I also worked on stabilizing the length of the optical fibres involved in this experiment, which in the end consisted of a ~75m long interferometer.These results represent the state of the art in terms of scalability for quantum repeaters using multimode memories and show that our system has a huge potential to enable the creation and transfer of quantum states over large distances.

Last update: 06/10/2022 04:45:23.

## List of lodged theses

• ALVAREZ ORTIZ, MARÍA MONSERRAT: Controlling the strong interaction between quantum emitters and plasmonic rod-dimers
Author: ALVAREZ ORTIZ, MARÍA MONSERRAT
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Deposit date: 29/09/2022
Thesis director: VAN HULST, NIEK | WOZNIAK, PAWEL
Committee:
PRESIDENT: GARCÍA PARAJO, MARÍA
SECRETARI: HÖFLICH, KATJIA
VOCAL: MIVELLE, MATHIEU
Thesis abstract: The growth of technology and climate change have increased the need for more efficient, biodegradable and ecologically sustainable electronic devices. With this in mind, different methods have emerged to improve the performance of organic materials. In particular, the union of plasmonic nanostructures with quantum emitters marked a new line of device research. The interaction between plasmons and quantum emitters led to the modification of the chemical properties of quantum emitters, which helped improve the absorption and emission capabilities of molecules. However, despite the efforts employed, reliable platforms to study the interaction between plasmons and molecules reproducibly have not yet been developed. This thesis aims to increase the interaction strength between plasmonic structures and organic molecules in a reproducible fashion by varying the optical properties of metallic structures. A fluorescent dye and a protein belonging to a photosynthetic bacterium were chosen as the systems to study. Consequently, the properties of the structures were tailored to obtain the desired optical response that matched the molecules/protein of interest. Mainly, the plasmonic structures' material, shape and size served to modify the resonance frequency and intensity of the near-field of the plasmon. In particular, this thesis investigated the plasmon interaction volume's effect on achieving and increasing the coupling strength. Fabrication of antennas by lithography, thermal evaporation, and helium ion milling allowed these properties to be modified. Nanorod dimer fabrication decreased the modal volume to less than 10 nm resolution. Characterising the structures was very important since the fine-tuning of the dimers led to different results. Here, darkfield confocal microscopy was used to analyse the plasmonic dimers' spectral response. In addition, finite difference time domain (FDTD) simulations provided information on the near-field strength in the dimer feeding space. Later, the molecules to the nanoantennas extended the study to coupled systems. Some systems showed a strong interaction between the dimers and the molecules/protein, which was identified by the mode splitting of the scattering spectra, the dispersion relation, and a comparison between coupling strength and individual system losses.

Last update: 06/10/2022 04:30:28.

## List of defended theses by year

• BERNARDELLO, MATTEO: Development of novel multimodal light-sheet fluorescence microscopes for in-vivo imaging of vertebrate organisms
Author: BERNARDELLO, MATTEO
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: LOZA ALVAREZ, PABLO | GUALDA MANZANO, EMILIO JOSE

Committee:
PRESIDENT: LORENZO, CORINNE
SECRETARI: KRIEG, MICHAEL
VOCAL: GONÇALVES MARTINS, GABRIEL JOSÉ
Thesis abstract: The observation of biological processes in their native environments is of critical importance for life science. While substantial information can be derived from the examination of in-vitro biological samples, in-vivo studies are necessary to reveal the complexity of the dynamics happening in real-time within a living organism. Between the possible biological model choices, vertebrates represent an important family due to the various characteristics they share with the human organism. The development of an embryo, the effect of a drug, the interaction between the immune system and pathogens, and the cellular machinery activities are all examples of highly-relevant applications requiring in-vivo observations on broadly used vertebrate models such as the zebrafish and the mouse. To perform such observations, appropriate devices have been devised. Fluorescence microscopy is one of the main approaches through which specific sample structures can be detected and registered in high-contrast images. Through micro-injections or transgenic lines, a living specimen can express fluorescence and can be imaged through such microscopes. Various fluorescence microscopy techniques have been developed, such as Widefield Microscopy (WM) and Laser Scanning Confocal Microscopy (LSCM). In WM the entire sample is visualized in a single 2D image, therefore losing the depth information, while LSCM can recover the 3D information of the sample but with inherent limitations, such as phototoxicity and limited imaging speed. In the last two decades, Light-Sheet Fluorescence Microscopy (LSFM) emerged as a technique providing fast and 3D imaging, while minimizing collateral damages to the specimen. However, due to the particular configuration of the microscope¿s components, LSFM setups are normally optimized for a single application. Also, sample management is not trivial, as controlling the specimen positioning and keeping it alive for a long time within the microscope needs dedicated environmental conditioning. In this thesis, I aimed at advancing the imaging flexibility of LSFM, with particular attention to sample management. The conjugation of these aspects enabled novel observations and applications on living vertebrate samples. In Chapter 1, a brief review of the concepts employed within this thesis is presented, also pointing to the main challenges that the thesis aims to solve.In Chapter 2, a new design for multimodal LSFM is presented, which enables performing different experiments with the same instrument. Particularly, high-throughput studies would benefit from this imaging paradigm, conjugating the need for fast and reproducible mounting of multiple samples with the opportunity to image them in 3D. Additionally, from this design, a transportable setup has also been implemented.With these systems, I studied the dynamics of the yolk¿s microtubule network of zebrafish embryos, describing novel features and underlining the importance of live imaging to have a whole view of the sample¿s peculiarities. This is described in Chapter 3.Further applications on challenging live samples have been implemented, monitoring the macrophage recruitment in zebrafish and the development of mouse embryos. For these applications, described in Chapter 4, I devised specific mounting protocols for the samples, keeping them alive during the imaging sessions.In Chapter 5, an additional LSFM system is described, which allows for recording the sub-cellular machinery in a living vertebrate sample, while avoiding its damage thanks to the devised sample mounting. Through this, single-molecule microscopy (SMM) studies, normally performed on cultured cells, can be extended to the nuclei of living zebrafish embryos, which better recapitulate the native environment where biological processes take place.Finally, Chapter 6 recapitulates the conclusions, the impacts, future integrations, and experimental procedures that would be enabled by the work resumed in this th

• BIANCHET, LORENA CECILIA: A versatile system for the study of light-matter interactions at the level of individual particles
Author: BIANCHET, LORENA CECILIA
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: MITCHELL, MORGAN

Committee:
PRESIDENT: BARREDO GONZALEZ, DANIEL
SECRETARI: CHANG, DARRICK
VOCAL: KAISER, ROBIN PIERRE LÉON
Thesis abstract: In this thesis, a single-atom trap in a "Maltese cross'' geometry (MCG) was designed, built up and characterized. A MCG atom trap uses four in-vacuum lenses to achieve four-directional high-numerical-aperture optical coupling to single trapped atoms and small atomic arrays. Here, we describe the theoretical background, the design, and the optical methods used for trapping and cooling atoms in a MCG geometry optimized for high coupling efficiency. We also characterize the resulting properties of the trap and trapped atoms. For this propose we measure occupancy, loading rate, lifetime, temperature, fluorescence anti-bunching and trap frequencies using current best practices. We also report another use of the optical control and coupling offered by the MCG: we use the two on-trap-axis lenses to produce a 1D optical lattice, the sites of which are stochastically filled and emptied by the trap loading process. The two off-trap-axis lenses are used for imaging and single-mode collection. Correlations of single-mode and imaging fluorescence signals are then used to map the single-mode collection efficiency.We observe trap characteristics comparable to what has been reported for single-atom traps with one- or two-lens optical systems. This shows that four-direction high-NA coupling can be achieved with little reduction in trap performance. Finally, we conclude with the near-future plans of the experiment.

• CASTILLA GÓMEZ, MANUEL SEBASTIÁN: Photodetectors based on graphene pn-junctions for mid-infrared and terahertz range
Author: CASTILLA GÓMEZ, MANUEL SEBASTIÁN
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: KOPPENS, FRANK

Committee:
PRESIDENT: SCALARI, GIACOMO
SECRETARI: PRUNERI, VALERIO
VOCAL: TREDICUCCI, ALESSANDRO
Thesis abstract: Long wavelength light contains the infrared and terahertz (THz) spetral range of the spectrum. This wavelength range spans approximately from 1 µm to 1 mm. Several applications can be explored in this spectral range such as thermal imaging, temperature monitoring, night vision, etc. Moreover, molecular vibrations resonate at these energies that are the fingerprints for compounds identification via molecular spectroscopy. Also, THz light has an important role in security since at these frequencies is possible to achieve a higher resolution for imaging compared to millimeter waves that are typically used in airports. Despite all these potential applications, long wavelength light technology still remains non-fully exploited. One of the reasons is due to the lack of competing instrumentation such as sources, modulators, detectors, sensors, etc. In particular, regarding the detectors, the commercially available technology present some issues such as working at room temperature, speed, sensitivity, dynamic range, broadband frequency operation, CMOS compatibility, size and compactness, etc. The extensive research during the last years on graphene and other 2D materials has opened new possibilities of novel light matter interactions that can unveil the next generation photodectectors and sensors, ascribed to the advantages respect to conventional semiconductors.In this thesis, we focus on developing novel photodetection platforms in the mid, longwave infrared and THz range based on graphene pn-junctions with integrated metallic nanostructures and hyperbolic 2D material. We have successfully integrated an antenna with a graphene pn-junction for highly sensitive and fast THz detection in this regime. This novel terahertz detector exploits efficiently the photothermoelectric (PTE) effect, based on a design that employs a dual-gated, dipolar antenna with a nanogap. We have demonstrated that this novel detector leads to an excellent performance, which fulfills a combination of figure-of-merits that is currently missing in the state-of-the-art detectors. We also overcame the main challenge of infrared photodetectors, which is to funnel the light into a small nanoscale active area and efficiently convert it into an electrical signal. We achieve this by efficient coupling of a plasmonic antenna to hyperbolic phonon-polaritons in hBN to highly concentrate mid-infrared light into a graphene pn-junction. We use a metallic bowtie antenna and H-shape resonant gates that besides concentrating the light into its nanogap, their plasmonic resonances spectrally overlap within the upper reststrahlen band (RB) of hBN (6-7 µm), thus launching efficiently these HPPs and guiding them with constructive interferences towards the photodetector active area. Additionally, by having two different antennas orientation, it allows us to have sensitive detection in two incident polarizations. Furthermore, we have shown mid and long-wave infrared photocurrent spectroscopy via electrical detection of graphene plasmons, hyperbolic phonon-polaritons and their hybridized modes. We combined in one single platform the efficiently excited polaritonic material that also acts as a detector itself. We identified peaks in the photocurrent spectra that evolves and blue shift by increasing the gate voltage, which are related to the polaritonic resonances. Finally, we investigated the electrical detection of molecular vibrations coupled to hyperbolic phonon polaritons in hBN. We detected this strong light-matter interaction via a graphene pn-junction placed at the vicinity of the molecules-hBN stack. The edges of the gap of the local gates launch efficiently the hBN HPPs that interact with the CBP molecular resonances that are spectrally located at the upper RB. We explored this interaction as a function of the thickness of the molecular layers, near and far field contribution, etc.

• DESHMUKH, CHETAN: Detection of a single erbium ion in a nanoparticle
Author: DESHMUKH, CHETAN
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: DE RIEDMATTEN, HUGUES

Committee:
PRESIDENT: NORTHUP, TRACY ELEANOR
SECRETARI: TARRUELL, LETICIA
VOCAL: SIMON, CHRISTOPH
Thesis abstract: Encoding information into quantum mechanical properties of a system can lead to applications many fields, including computing and communication. Devices that will enable these applications could be part of a quantum network in the future. Quantum networks can be implemented using nodes that have the ability to generate and store entanglement efficiently for long durations as well as to process quantum information. The nodes also need to be interfaced with photons, which can faithfully carry information over long distances. Single rare-earth ions doped in crystals offer all these capabilities. The main goal of this thesis was to detect a single erbium ion, which operates in the telecommunication wavelength, and to investigate its feasibility as a spin-photon interface.Detecting a single erbium is challenging due to its low emission rate, but it can be aided by Purcell-enhancing its emission via coupling to an optical cavity. In this thesis, we utilize erbium ions doped into nanoparticles, which facilitates their integration into cavities with small mode-volumes. In addition, nanoparticles provide the confinement required to individually manipulate spatially close-by single ion qubits, which is required for dipolar quantum gates. We hence first study the optical coherence properties of Er:Y2O3 nanoparticles at cryogenic temperatures. We identify the limiting mechanisms and identify avenues for improvement in the future. We also study the optical and spin coherence properties of Pr:Y2O3, which is a promising alternative to erbium.Fiber-based microcavities can achieve high Purcell factors as they can simultaneously realize high finesse and small mode-volume. They are also ideally suited to be coupled to nanoparticles due to their tuning capabilities. However, stabilizing such a cavity inside a cryogenic environment is challenging. We hence first describe the construction of a custom setup, which enables us to stabilize the cavity while being coupled to a suitable nanoparticle. Utilizing the first iteration of this setup, we then report on the coupling of Er:Y2O3 nanoparticles to a fiber-based high finesse microcavity. We achieve an average Purcell factor of 14 for a small ensemble of ions, while a small subset of ions show Purcell factor up to 70. We explain the obtained multi-exponential decay behaviour using a detailed model. Furthermore, we demonstrate dynamic control of the Purcell-enhanced emission by tuning the cavity resonance on a time-scale faster than the spontaneous emission rate of the ions. This allows us to extract the natural lifetime of the ions as well as to shape the waveform of the emitted photons. However, we conclude that the achieved signal-to-noise ratio is not high enough to resolve single erbium ions.For the final experiment, we operate the second iteration of the setup, which improves our sensitivity to single erbium ions by more than a factor 50. This enables us to demonstrate the first detection of a single erbium ion in a nanoparticle. The ion exhibits a Purcell factor of 60, leading to a cavity enhanced lifetime of 225 us, and a homogeneous linewidth of 380 MHz. The counts received from the ion show a clear saturation and we measure the second-order auto-correlation of the emitted photons to be 0.59, which reduces to 0.29 after background-subtraction. This is strong evidence that the photons are emitted by a single erbium ion. Our work opens the path for exploring single rare-earth-ions doped into nanoparticles as spin-photon interfaces for quantum information processing.

• ELU ETXANO, UGAITZ: High-peak-power mid-infrared OPCPAs for extreme nonlinear photonics
Author: ELU ETXANO, UGAITZ
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: BIEGERT, JENS

Committee:
PRESIDENT: CHALUS, OLIVIER
VOCAL: NOVOA FERNÁNDEZ, DAVID
Thesis abstract: In the last decades, intense carrier-envelope-phase-stable (CEP-stable) and near-single-cycle, coherent mid-infrared sources have become charming for a variety of applications in physics, chemistry and biology. In particular, those mid-infrared sources are of tremendous interest for broadband spectroscopic applications, solid-state light-matter studies, strong-field physics research, and attosecond science. On the one hand, broadband coherent mid-infrared sources are capable of replacing time-consuming scanning techniques to classify organic structures or detect hazardous chemical compounds. On the other hand, high-energy, CEP-stable, near single-cycle mid-infrared sources are key in strong-field physics and attoscience due to the wavelength scaling nature of strong-field electron re-collision-based processes.Nevertheless, implementing such mid-infrared sources remains challenging due to the lack of user-friendly temporal, spectral and spatial characterisation instruments, efficient and affordable reflection/transmission coatings, and commercially accessible low-loss dispersion compensation optics. Moreover, the absence of suitable laser gain materials reinforces nonlinear down conversion and amplification methods. One approach to overcoming the current limitations and developing intense ultrafast mid-infrared systems is to use a commercially available high-power near-infrared laser combined with second-order nonlinear processes such as the optical parametric amplification (OPA) process or the optical parametric chirped-pulse amplification (OPCPA) process. OPCPA can be essential to avoid damage to the nonlinear crystals or tailor the amplified spectrum. OPCPAs are also used when femtosecond pulses are required to be amplified using picosecond pump lasers. As a result, OPCPA systems offer novel opportunities for producing high-intensity, broadband mid-infrared femtosecond pulses.Here the 160 kHz high-power mid-infrared OPCPA system is developed to overcome the existing limitations in the high-repetition-rate mid-infrared regime. This thesis demonstrates the generation of unique 3.2 µm pulses with a single-cycle duration and delivering up to 3.9 GW of peak power. The combination of the CEP stability with the single-cycle duration and the high energies demonstrated makes this system suitable to produce ultrafast radiation in the kilo-electron-volt X-ray regime.A newly developed mid-infrared nonlinear crystal named BGGSe is proposed for efficient broadband infrared radiation generation. The ultra-broadband source is produced using the BGGSe crystal combined with a unique anti-resonant-reflection photonic crystal fibre (ARR-PCF) that enables tailoring the compression of our 3.2 µm pulses at 160 kHz. Using the BGGSe crystal and the ARR-PCF, we demonstrate the generation of coherent light expanding up to seven octaves, from UV to the THz regime.The second mid-infrared system presented in this thesis is the high-energy 7 µm OPCPA operated at a 100 Hz repetition rate and developed to generate hard X-rays in the multi-kilo-electron-volt regime. The development of this second OPCPA centred at 7 µm overcomes the considerable challenges in the mid-infrared regime. This thesis demonstrates the amplification of those mid-infrared pulses to 750 µJ and the efficient back-compression to 188 fs.Moreover, high harmonic generation in solids driven by 7 µm pulses at 100 Hz and 3.2 µm pulses at 160 kHz has been exploited for solid-state studies using the developed OPCPA systems. This thesis highlights the results achieved in the high-temperature YBCO superconductor, where exponential enhancement of harmonics is demonstrated below the critical temperature.All these demonstrations make those systems a key-enabling technology for the next generation of studies in solid-state physics, extreme nonlinear photonics, strong-field physics and coherent X-ray science.

• FRÖLIAN, ANIKA: Simulating a topological gauge theory in a Raman-dressed Bose-Einstein condensate
Author: FRÖLIAN, ANIKA
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: TARRUELL, LETICIA

Committee:
PRESIDENT: ÖHBERG, PATRIK JAN PETER
SECRETARI: DE RIEDMATTEN, HUGUES
VOCAL: BEUGNON, JÉRÔME CHRISTOPHE
Thesis abstract: Ultracold quantum gases constitute a powerful and versatile tool to experimentally explore quantum many-body physics. This thesis presents an original contribution to the quantum simulation of gauge theories with ultracold atoms, which has evolved into a thriving research field during the last years. Gauge theories form the basis of our modern understanding of nature, with applications ranging from high energy to condensed matter physics. A subclass formed by topological gauge theories plays a key role in the effective description of certain strongly correlated materials. An important example is the fractional quantum Hall effect, where the topological Chern-Simons theory can provide an effective single-particle description for some of the filling factors. A simpler toy model which already provides access to the key properties of topological gauge theories is the one-dimensional chiral BF theory obtained from Chern-Simons theory after dimensional reduction. This thesis reports on the quantum simulation of the chiral BF theory in an ultracold gas of bosonic potassium atoms, establishing ultracold quantum gases as a resource for the quantum simulation of topological gauge theories. As a first step, we establish the theoretical framework necessary for the quantum simulation of the chiral BF theory. We start by deriving an encoded Hamiltonian for this gauge theory in which the gauge degrees of freedom are eliminated via the local symmetry constraint. The encoding results in a system with only matter particles that have local but unconventional chiral interactions. We continue by showing that these chiral interactions can be realized in a Raman-dressed Bose-Einstein condensate (BEC) with unbalanced interactions by deriving an effective single-component Hamiltonian from a microscopic view in momentum space.Subsequently, we present the implementation of the different ingredients necessary to realize the chiral BF theory in our experiment. In a first series of experiments, we study the effects of coherent coupling on the effective collisional properties of the system. To this end, we employ radio-frequency to couple two internal states with unequal interaction in a 39K BEC. We measure the effective scattering length of the system as a function of the coupling field parameters. Moreover, we use the coherent coupling as an interaction control tool and quench the effective interactions from repulsive to attractive values. Afterwards, we turn to the implementation of Raman coupling and characterize the modifications in the dispersion of Raman-dressed atoms at the single particle level. Finally, we demonstrate the realization of the chiral BF theory by combining Raman coupling and unbalanced interactions in a BEC of 39K. We probe the chiral interactions arising in the system and observe the formation of chiral bright solitons which dissolve as soon as their propagation direction is inverted. Moreover, we use the local symmetry constraint of the theory to reveal the BF electric field through measurements on the matter field alone, and show that it leads to an asymmetric expansion of the condensate. Our experiments establish chiral interactions as a novel resource for quantum simulation experiments and pave the way towards implementing topological gauge theories in higher dimensions with ultracold atoms.

• HUSSAIN, RUBAIYA: Detection of particles, bacteria and viruses using consumer optoelectronic components
Author: HUSSAIN, RUBAIYA
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: PRUNERI, VALERIO

Committee:
PRESIDENT: KERSAUDY-KERHOAS, MAÏWENN
VOCAL: MANNELLI, ILARIA
Thesis abstract: The focus of this thesis is on the design, development and validation of two novel photonic sensors for the detection and characterisation of industrial and biological samples. The first one is a PSA in a collimated beam configuration using an innovative angular spatial filter, and a consumer electronic camera similar to that used in a smartphone. The small form factor angular spatial filter allows for the collection of diffused light from particles up to predefined discrete angles. By using angularly resolved scattering images acquired by the camera, a machine learning (ML) algorithm predicts the volume median diameter of the particles. Our system has achieved a mean absolute percentage error of only 0.72% for spherical particles in solution with sizes greater than 10 µm and at concentrations up to 40 mg mL-1. Compared to traditional laser diffraction systems, the proposed PSA is an order of magnitude smaller in size, weight and cost, and offers a promising approach to online industrial process monitoring.As light scattering is influenced by factors other than particle size, including shape, refractive index contrast and suspension concentration, the PSA can also be employed in biological applications. To this end, the second part of the thesis aims to optimise the PSA for the measurement of small (< 10 µm) particles such as microorganisms. The results demonstrate that the modified PSA in combination with ML is able to accurately classify different types of bacteria (Escherichia coli and Enterococcus sp.) and distinguish them from silica beads of comparable sizes, with an accuracy of 89%. Moreover, it can detect the concentration of bacteria in water with a limit of detection (LOD) of approximately 105 cells mL-1.The final part of the thesis is dedicated to the development of a low-cost, portable optical biosensor for the specific detection of particles smaller than bacteria, such as viruses (< 1 µm). The proposed system, which we have called flow virometry reader (FVR), is a modification of a flow cytometer and relies on measuring light emissions from fluorescent antibodies that bind to specific viral particles. An LOD of 3,834 copies mL-1 for SARS-CoV-2 in saliva can be achieved with the device. The FVR is clinically validated using 54 saliva samples in a blind test, with high sensitivity and specificity of 91.2% and 90%, respectively. These findings suggest that the FVR has the potential to be a highly viable alternative to current diagnostic methods for pandemic events, as it is faster (< 30 min) and less expensive than PCR tests, while being more sensitive than today¿s COVID-19 rapid antigen tests.The photonic sensing technologies developed in the thesis show significant potential for use in a wide range of applications, including:¿ particulate air pollution, causing cardiovascular and respiratory problems¿ particulate water pollution, which affects the ecosystems of rivers, lakes and oceans¿ total bacterial count in environmental or bathing water¿ viral pandemics The technologies are particularly appealing in countries with limited resources due to their simple design, portability, short time-to-result and affordability, as well as the fact that they do not require a specialised laboratory or trained personnel to operate them.

• JULIÀ FARRÉ, SERGI: Controlling interactions in quantum materials: from a microscopic description to quantum simulation
Author: JULIÀ FARRÉ, SERGI
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: LEWENSTEIN, MACIEJ | DAUPHIN, ALEXANDRE

Committee:
PRESIDENT: WEITENBERG, CHRISTOF
SECRETARI: ASTRAKHARCHIK, GRIGORI
VOCAL: BERMÚDEZ CARBALLO, ALEJANDRO
Thesis abstract: The last decades have witnessed impressive technical advances in all the fields of quantum science, including solid-state systems or atomic, molecular, and optical physics, allowing one to control materials at the microscopic scale with a high degree of precision. This development opens the road for the investigation of complex many-body phenomena in quantum materials, which cannot be easily inferred from the behavior of their individual constituents. Indeed, interactions in quantum many-body systems can lead to richer physics compared to the noninteracting case, as they are deeply connected with spontaneous symmetry breaking, quantum correlations, i.e., entanglement, and some collective behaviors. On the one hand, in some cases, the motivation to study such interacting systems is the possibility to synthesize them in the lab, such as for instance with cold atoms in optical lattices. The latter platform can be used as a quantum simulator of systems that were regarded just as toy models in the last century, as it is the case of topological insulators: materials characterized by a global topological invariant leading to protected surface modes. While so far experiments have concentrated their efforts on engineering noninteracting topological insulators, state-of-the art techniques can also be used to study the role of interactions in these systems.In this context, the first goal of this thesis is to investigate novel effects in interaction-induced topological insulators. In the one-dimensional case, we reveal the topological nature of fermionic chains with frustrated interactions, which could be realized with dipolar quantum gases. For the two-dimensional case, we focus on topological Mott insulators, for which we propose an experimental scheme based on Rydberg-dressed atoms. Furthermore, we show that these systems can exhibit rich spatial features intertwined with their topological protection, owing to the interacting nature of the phase. On the other hand, there are some paradigmatic cases, as in high-Tc superconductors, where exotic experimental results clearly point towards the need of finding a microscopic model in a many-body interacting framework. In the particular case of high-Tc superconductors, their complex composition and unknown exact form of intrinsic interactions make it challenging to characterize their rich phase diagram: such materials not only host a high-Tc superconducting phase, but also other exotic phases, such as the strange metal or pseudogap phases. In this regard, the second goal of this thesis is to gain physical insight of the pseudogap phase of cuprate high-Tc superconductors. To this aim, we numerically study the effect of interactions between electrons and bond phonons within a particular Hamiltonian modeling of the system. We show that, by properly accounting for the subtle interplay between electron-electron and electron-phonon interactions, one can indeed numerically reproduce the main experimental features of the pseudogap phase.Finally, the study of collective interaction-induced effects is also needed to analyze the quantum advantage theoretically claimed for some systems. In particular, many-body interactions and entanglement are sometimes regarded as a resource for quantum thermodynamic machines: devices that perform tasks related to refrigeration, heat-to-work conversion, or energy storage. On this basis, the third goal of this thesis is to study fundamental bounds imposed by quantum mechanics to collective charging effects in systems for energy storage, called quantum batteries.

• KEARY, SARAH: Spatiotemporal organisation of protein nanoclusters in adhesion complexes
Author: KEARY, SARAH
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: GARCÍA PARAJO, MARÍA | CAMPELO AUBARELL, FELIX

Committee:
PRESIDENT: BRASSELET, SOPHIE
SECRETARI: KRIEG, MICHAEL
VOCAL: ROCA-CUSACHS SOULERE, PERE

• LIU, XINYAO: Atomic imaging of complex molecular
Author: LIU, XINYAO
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: BIEGERT, JENS

Committee:
PRESIDENT: GONZÁLEZ FEREZ, ROSARIO
SECRETARI: LEWENSTEIN, MACIEJ
VOCAL: GRÄFE, STEFANIE
Thesis abstract: One of the significant challenges of modern science is to track and image chemical reactions as they occur. The molecular movies, the precise spatiotemporal tracking of changes in their molecular dynamics, will provide a wealth of actionable insights into how nature works. Experimental techniques need to resolve the relevant molecular motions in atomic resolution, which includes (10^(-10) m) spatial dimensions and few- to hundreds of femtoseconds (10^(-15) s) temporal resolution. Laser-induced electron diffraction (LIED), a laser-based electron diffraction technique, images even singular molecular structures with combined sub-atomic picometre and femto-to attosecond spatiotemporal resolution. Here, a laser-driven attosecond electron wave packet scatters the parent¿s ion after photoionization. The measured diffraction pattern of the electrons provides a unique fingerprint of molecular structure. Taking snapshots of molecular dynamics via the LIED technique is proved to be a potent tool to understand the intertwining of molecules and how they react, change, break, bend, etc. This thesis is especially interested in exploiting advanced LIED imaging techniques to retrieve large complex molecular structures. So far, LIED has successfully retrieved molecular information from small gas-phase molecules like oxygen (O2), nitrogen (N2), acetylene (C2H2), carbon disulfide (CS2), ammonia (NH3) and carbonyl sulfide (OCS). Nevertheless, most biology interesting organic molecules typically exist as liquid or solid at room temperature. In order to accomplish the final goal to extract these larger complex molecular structural information, we need to overcome two main challenges: delivering the liquid or solid samples as a gas-phase jet with sufficient gas density in the experiment and developing a new retrieval algorithm to extract the geometrical information from the diffraction pattern. We tested one of the most simple liquid molecules - water H2O in the reaction chamber as a primary step. We traced the variation of H2O+ cation structure under the different electric fields. To solve the problem of unsatisfactory gas density, we present a novel delivery system utilizing Tesla valves that generates more than an order-of-magnitude denser gaseous beam. Machine learning is well qualified to solve difficulties with manifold degrees of freedom. We use convolutional neural networks (CNNs) combined with LIED techniques to enable atomic-resolution imaging of the complex chiral molecule Fenchone (C10H16O).

• OLIVEIRA DE ALMEIDA, JESSICA: Quantum Optics at its best: from quantum interferometry to quantum metrology
Author: OLIVEIRA DE ALMEIDA, JESSICA
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: LEWENSTEIN, MACIEJ | SKOTEINOTIS, MICHALIS

Committee:
PRESIDENT: SANCHEZ SOTO, LUIS LORENZO
PRESIDENT: ACÍN DAL MASCHIO, ANTONIO
Thesis abstract: Quantum optics experiments are currently the most advanced techniques to under- stand, verify and simulate quantum phenomena. However, to access all the perfor- mance available in quantum states of light, one needs to address fundamental opera- tional limits. In quantum mechanics, the measurement strategy affects the quantum state; therefore, to access all the degrees of freedom available in the quantum states, one must implement the optimal feasible measurement. In this thesis, I investigate how to perform more precise measurements in optics, namely slit-interference and image resolution, by exploiting the quantum mechanical nature of light. A complete description of multi-slit interference must include nonclassical paths, Feyn- man paths that goes through two or more slits. Prior work with atomic interference in the double-slit experiment with cavities as which-way detectors, has shown these paths to be experimentally inaccessible. In this thesis I show how such a setup can detect nonclassical paths with 1% probability, if different nonclassical paths are in- cluded. I also show how this setup can be used to erase and restore the coherence of the nonclassical paths. In the same chapter I demonstrate how the same setup could implement an exact measure of Born-rule violation. And in the last part I debate about the figures of merit in the literature to test the Born-rule. During more than one century, there was a fundamental limit on image resolution; due to diffraction effects in finite detectors apertures, one cannot resolve two incoher- ent sources very close to each other, e.g. stars. In the last decade, the formalism of quantum information allowed new proposals for sub-diffraction limited resolution or super-resolving measurements. Nevertheless, these measurements are susceptible to misalignment. In this thesis, I suggest alternative measurement strategies to incorpo- rate misalignment in super-resolution imaging, showing that sub-diffraction limited resolution is still possible. The proposed measurements can be implemented using linear optical transformations and offer an advantage in the case of estimation and discrimination of two incoherent point sources allowing one to quantify the mitigat- ing effects of misalignment. Moreover, I propose a collective measurement strategy, on two or more photons, that estimates the separation between two incoherent point sources and is oblivious to misalignment. In an optics experiment, the quantum state verification relies on tomography measure- ments on copies of the prepared state. The error in tomography experiments is called confidence region, and it defines the region in which the quantum state is found with the desired probability. There are different methods to compute confidence regions; in this thesis, I analyze the capability of the known methods by resolving two nearby quantum states using a finite amount of measurement data.

• ÖZDEMIR, ONUR: Further Into the Infrared With Quantum Dot Photodetectors
Author: ÖZDEMIR, ONUR
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: KONSTANTATOS, GERASIMOS

Committee:
PRESIDENT: MARTIN GARCIA, BEATRIZ
SECRETARI: GARCÍA DE ARQUER, FRANCISCO PELAYO
VOCAL: CURRY, RICHARD JAMES
Thesis abstract: In the infrared, photodetectors are the key components in a wide-variety of applications such as thermal imaging, remote sensing, spectroscopy with newer technologies added to the list such as LiDaR and deep tissue imaging. As the demand for photodetectors increase with a shift towards longer wavelengths, we need high-performance, scalable and low-power consuming alternatives to current infrared photodetector technologies.Colloidal Quantum Dots (CQDs) are nanoscale-sized semiconductors with quantum-confined charges in all 3 dimensions. They can be synthesized in solution and can easily be deposited onto a desired substrate as a quantum dot (QD) film which allows easy integration with current silicon-based technologies. QDs are efficient light absorbers and their bandgap can accurately be tuned by controlling their size during synthesis. Lead chalcogenide QDs, such as PbS and PbSe, have tunable bandgaps covering the near-infrared (NIR) and short-wave infrared (SWIR) up to 3 µm, making them ideal sensitizers for photodetectors.In this thesis, we utilize PbS QDs with an excitonic bandgap around 1.8 µm in combination with 2-dimensional transition metal dichalcogenides (TMDCs) to form hybrid photodetectors operating in the infrared. With their layered structure similar to graphene and semiconducting character, TMDCs have outstanding electronic properties. Incorporating few-layers of TMDCs in our PbS QD detectors allows fast and efficient charge transfer from the QDs to the photodetector contacts through the TMDC layer, boosting detector responsivity. By combining PbS QDs with two types of TMDCs, WS2 and MoS2, we are able to reach detectivities exceeding 1012 Jones at room temperature with a response up to 2 µm.Probing further into the infrared, we extend the spectral response of our hybrid detectors up to 3 µm by utilizing narrower-bandgap PbSe QDs with MoS2 layers.After a careful analysis and using strategies such as oxide-isolation of metallic contacts, we reached detectivities of 7.7 x 1010 Jones at 2.5 µm at RT. With their low-noise and high responsivities, our detectors improve the potential of hybrid detectors and demonstrate a performance comparable to commercial detectors without the need of external cooling, costly vapor deposition techniques or complex integration with silicon technology.Broadening the reach of PbS QDs even further, even beyond the limit of their bulk bandgap, up to 9 µm by using a novel doping method, we demonstrate the first PbS QD intraband photodetectors. Having developed this air-stable high n-doping method for PbS QDs, observation of intraband transitions taking place between the first two conduction levels becomes possible. These intraband transitions have lower energies compared to the bandgap, opening up another degree of freedom in tunable optical response of our QDs between 6-9 µm. We study how the doping works across a wide range of QD sizes and at different temperatures. Our photodetectors utilizing the intraband transitions in highly-doped PbS QD films have detectivities approaching 105 Jones.To sum up, we demonstrated lead chalcogenide QD based photodetectors with improved performance and spectral responses progressively shifting deeper into the infrared. Our TMDC-QD hybrid detectors reveal the potential of these systems as alternatives to commercial detectors. Whereas, surpassing the bandgap limit with high doped QDs and intraband transitions opens up new ways to realize optoelectronic devices further in the infrared.

• PÉREZ SALINAS, DANIEL: Inhomogeneity and disorder in ultrafast phase transitions
Author: PÉREZ SALINAS, DANIEL
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: WALL, SIMON ELLIOT

Committee:
PRESIDENT: MIHAILOVIC, DRAGAN DRAGOLJUB
SECRETARI: VAN HULST, NIEK
VOCAL: RETTIG, LAURENZ
Thesis abstract: In the recent decades, there has been a surge of interest in the wide array of emergent phenomena found in strongly correlated materials. Understanding the inner workings of this type of systems is a major challenge due to the complex way in which multiple degrees of freedom, such as electronic, structural and spin, interact with each other and themselves in non-trivial fashion. One of the most striking outcomes of these subtle interactions in correlated materials is the richness of their phase diagrams, which include exotic states that still elude a complete physical description. It is in the transition from one phase to another where the insights into the complex microscopic mechanisms may be most readily found, and so the study of phase transitions has become a staple in correlated materials science.The experimental techniques used to track phase transitions are steadily becoming more precise and, with the improvements, previously overlooked aspects of a phase transition become more apparent, such as inhomogeneity or disorder, which add another layer of complexity that may clash with our current understanding. This is particularly important in the relatively young field of ultrafast studies of correlated materials, which tackles these systems in a largely uncharted territory: non-equilibrium situations. In this thesis, we develop novel experimental techniques which push towards an assessment of disorder and/or inhomogeneity in non-equilibrium phase transitions, while still being able to accurately track the dynamics of the degrees of freedom involved. We then apply these techniques in two systems of current interest: La0.5Sr1.5MnO4, a prototypical layered manganite, and VO2, one of the most emblematic correlated materials.For La0.5Sr1.5MnO4, we introduce an all-optical tabletop pump-probe setup that is able to track the ultrafast melting of charge- and orbital-order parameter with high accuracy. We show how, in contrast with previous descriptions, the transition is incoherent and fits with the paradigm of an order-disorder process. A key factor in these dynamics, which is sometimes overlooked, is spatial phase separation into the depth of the material. With our setup, the role of initial inhomogeneity and its evolution can be readily tested. For VO2, we employ facility-scale X-ray sources to directly image phase inhomogeneity in the metal-to-insulator transition with coherent X-ray diffraction techniques. We show quantitative imaging of phase separation and domain growth statically, which in our experimental setups should be able to distinguish intermediate phases appart from the usual monoclinic insulator and rutile metal. We find no evidence of previously claimed intermediate phases such as monoclinic metal VO2. Finally, we show the first non-scanning spatially-resolved observation of the ultrafast phase transition in VO2 with nanometer resolution, where we identify a global, prompt change in the domain pattern in the femtosecond scale.

• ROMBAUT SEGARRA, JUAN: Multifunctional optical surfaces for optoelectronic devices
Author: ROMBAUT SEGARRA, JUAN
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Temporary seizure
Thesis director: PRUNERI, VALERIO

Committee:
PRESIDENT: MANNELLI, ILARIA
SECRETARI: MARTORELL PENA, JORDI
VOCAL: ST CLAIR, TODD PARRISH
Thesis abstract: Highly transparent optical surfaces with anti-reflection (AR) and self-cleaning properties have the potential to increase performance in a wide range of applications, such as display screens, photovoltaic cells or sensors. Nature has provided numerous examples of biological systems with interesting functionalities that have high commercial interest, from the broadband and omnidirectional anti-reflection effect created by the tiny nanopillars found on the corneas of moths¿ eyes, to the self-cleaning behaviour of lotus leaves generated by micro-and nanoprotuberances. However, despite intense academic research, replicating such elaborate nanostructures for mass-production remains a major challenge due to the limitations of the existing nanofabrication techniques based on classical optical and e-beam lithography processes. This thesis is devoted to the study of bio-inspired multifunctional nanostructured surfaces with enhanced optical and wetting properties for use in optoelectronic devices. Novel and reliable manufacturing techniques are proposed for patterning organic and inorganic materials with high precision and throughput, aiming to bring this technology out of the laboratory and making it industrially viable. The first part of this study has been centred on glass, as it is one of the most widely used materials for optoelectronic devices. Chapter 3 presents a nanopillar structure created on glass substrates, which provides high anti-reflective properties, enhanced transmission, superhydrophobicity, and high mechanical resistance against external agents. The proposed manufacturing method permits moderate tunability to adapt the structure to the requirements of different applications. The design and optimisation of the fabrication process and a full characterisation of the samples are reported. Chapter 4 describes the combination of two different anti-reflective approaches, state-of-the-art multilayer (ML) anti-reflective coatings and self-cleaning biomimetic nanostructures (NS). The classical ML coating, relying on destructive interference from multiple reflections at layer interfaces is capable of providing excellent AR properties, but with a limited wavelength range and angular acceptance. In addition, it has limited hydrophobicity and self-cleaning properties due to its flat surface. The NS coating can provide broad wavelength and angular AR properties, as well as superhydrophobicity. However, it suffers from mechanical durability issues. In this work, the combination of both methods is presented as an innovative solution, combining greater anti-reflective operational wavelength and angular acceptance, self-cleaning properties, and high mechanical durability. A nanostructured design for transparent oleophobic surfaces is investigated and experimentally demonstrated in Chapter 5. Two new fabrication techniques to create nanocavities on glass are presented. The nanohole structure can repel oil and other low surface tension liquids, and a new wetting model is developed to theoretically explain the mechanism. The porous structure modifies the effective refractive index of the nanostructured layer between the air and the glass, creating an AR effect. The samples present higher transmission, as well as low scattering due to the subwavelength size of the cavities. In addition, the geometry of the surface offers higher mechanical resistance compared to nanopillars, widening the potential applications where it could be used. Finally, in Chapter 6, a new method to nanostructure organic materials with high resolution is presented. Nanostructured thin polyimide films on top of glass surfaces can act as an anti-reflective coating, while adding protection and hydrophobicity. A practical example is demonstrated with transparent electrodes made of Indium Tin Oxide. By covering a surface with nanostructured polyimide, the overall optical response can be improved while its electric properties are protected by the polymeric film.

• SANCHEZ, AURELIEN: Laser-induced electron interferences from atoms and molecules
Author: SANCHEZ, AURELIEN
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: BIEGERT, JENS

Committee:
PRESIDENT: SENFTLEBEN, ARNE
SECRETARI: LEWENSTEIN, MACIEJ
VOCAL: FIGUEIRA DE MORISSON FARIA, CARLA
Thesis abstract: Since discovering wave-particle duality, science has changed our perception of light and matter, especially at the subatomic level. Thanks to such discoveries, we have been able to develop and expand our scientific knowledge over the past two centuries, crossing those limits. For instance, let us take the famous double-slit experiment from T. Young (1801). This experiment has been extended after the twentieth-century quantum revolution, revealing electron and neutron diffraction used nowadays to measure the nuclei separation from complex structures. Similarly, the experiment of Michelson and Morley (1887), which follows T. Young foundations, got a fair success in astronomy, enabling high-resolution imaging of stars in the universe. In this thesis, we use light to generate electrons and produce interferences similar to the double-slit experiment, which is analyzed further to study the atomic properties.On the dynamics of an atom, that is, attoscience, we use ultrafast laser pulses to trigger motions on a femtoseconds time-scale.Together with the use of strong intense laser fields in the Mid-IR regime, the electron is ionized with zero-kinetic energy and subsequently accelerated by the laser ponderomotive energy.Strong field dynamics offer rich structures that are encoded in the photoelectron momentum distribution. Since we use two-color combined laser fields, we can gate and control those dynamics further down on the sub-cycle scale. More precisely, we show that with the help of a Reaction Microscope, we can extract both electron information and nuclear dynamics within extraordinary sub-cycle temporal resolution.Finally, the strong-field recollision model is investigated with molecules through the previously developed laser-induced electron diffraction (LIED) method. We show that backscattered electron interferences, issued from strong field at low impact parameters, embedded a particular molecular orientation that can be reproduced when the molecule is considered aligned with the laser field polarization. Those findings seem to encode a more profound property about wave diffraction in molecules until recently unexplored due to the imposed conditions given in conventional electron diffraction (CED).

• SUKEERT, SUKEERT: Versatile nonlinear frequency conversion sources in the near- and mid-infrared
Author: SUKEERT, SUKEERT
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal

Committee:
PRESIDENT: AGNESI, ANTONIANGELO
SECRETARI: LOZA ALVAREZ, PABLO
VOCAL: PEDERSEN, CHRISTIAN
Thesis abstract: Tunable laser sources in different spectral regions are of interest for a variety of applications including spectroscopy, trace gas sensing, medical diagnostics, LIDAR and material processing. Existing lasers have limited tunability and many spectral regions continue to remain inaccessible to lasers due to lack of suitable gain media. Nonlinear frequency conversion is a viable approach to cover such difficult spectral regions in the visible, near and mid-infrared (mid-IR). Optical parametric oscillators (OPO) can provide wide wavelength tunability with high output powers in good beam quality across continuous-wave (cw), nanosecond and ultrafast picosecond and femtosecond time-scales. With the development of quasi-phase-matched (QPM) nonlinear materials in fan-out grating structure, wide wavelength tuning is possible at a fixed temperature, enabling the development of rapidly tunable devices for practical applications. Difference-frequency-generation (DFG) is also an attractive approach for generating high powers in the mid-IR in a single-pass scheme. In this thesis, we have developed second-order nonlinear frequency conversion sources based on nanosecond and cw OPOs and cw DFG. Widely tunable green-pumped OPOs have been developed by using fan-out grating structure for the first time in different nonlinear materials, and a high-power cw source in the mid-IR has been developed by exploiting DFG. The sources developed in this thesis cover a wavelength range spanning 677-2479 nm. One of the OPOs developed in this work has also been deployed in an industrial environment in a device characterization setup. In green-pumped OPOs, we demonstrate a widely tunable cw OPO based on PPKTP in a fan-out grating structure. The OPO is continuously tunable across 742-922 nm in the signal, and 1258-1884 nm in the idler. Resonant wave output coupling has been deployed to extract useful signal power and reduce the thermal load, and the OPO can deliver up to 1.65 W of total output power. The use of output coupling results in superior performance of the OPO over pure singly-resonant oscillator (SRO) configuration. We also develop the first green-pumped OPO based on MgO:cPPLT. Continuous wavelength tuning across 689-1025 nm in the signal and 1106-2336 nm in the idler at room temperature has been achieved in the nanosecond OPO by using a fan-out grating structure. The OPO can provide up to 131 mW of average output power at 25 kHz repetition rate, and the idler passive power stability is 3.9% rms over 30 minutes. A cw OPO based on MgO:PPLN in a fan-out grating design is then described. The OPO is continuously tunable across 813-1032 nm in the signal and 1098-1539 nm in the idler. A short crystal length and signal output coupling are used to minimise thermal effects, and the OPO can generate up to 710 mW of total output power with signal and idler passive power stabilities better than 2.8% rms and 1.8% rms, respectively over 1 hour and signal M^2<1.1. As a part of an industrial internship, a cw green-pumped MgO:PPLN OPO is developed at Radiantis. The OPO is used as the input light source of a device characterization setup to test sensors for the aerospace sector. Compared to the existing light source, using the OPO results in orders-of magnitude-higher response of the InGaAs sensor, leading to a more precise and accurate characterization, and lower measurement error, thus improving the device evaluation process. Finally, we demonstrate a high-power cw source at 2.26 µm using the DFG process. The source can deliver up to 3.84 W of output power at 2262 nm, with a power stability better than 0.6% rms over 1 hour, in a Gaussian mode profile with M^2<1.2.

• TAGLIABUE, SUSANNA: Comprehensive monitoring of the injured brain by hybrid diffuse optics: towards brain-oriented theranostics
Author: TAGLIABUE, SUSANNA
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Temporary seizure
Thesis director: DURDURAN, TURGUT | KACPRZAK, MICHAL

Committee:
PRESIDENT: BHATTACHARYA, NANDINI
SECRETARI: GARCÍA DE ARQUER, FRANCISCO PELAYO
VOCAL: GIACALONE, GIACOMO
Thesis abstract: In the intensive care, the multimodal monitoring of the patient is crucial. The systemic physiology is routinely and comprehensively monitored but the practical monitoring of the brain is lacking. Hybrid diffuse optics (DO) has a potential to fill this gap by combining diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS). DO measures local, microvascular cerebral perfusion/blood flow, oxygen extraction fraction and cerebral metabolic rate of oxygen. Therefore, the overarching purpose of this work was to boost the use of hybrid DO by validating its utility in clinical applications on the human brain, especially in critically ill populations. To achieve this goal, new hybrid DO devices were constructed to enhance the data-rate and the quantification of the intracerebral signals while synchronously acquiring data from clinical monitors. In particular, a new platform combining time-resolved NIRS (TRS) and fast (~40 Hz) DCS was constructed.These were used in the fruitful collaborations with the Vall d'Hebron hospital on different patient cohorts. In a population of patients undergoing surgeries the relationship with electrophysiological assessment of cerebral metabolism, the proprietary bispectral index, and the optically-derived parameters were investigated during propofol-induced anesthesia. This has shown that DO estimates of the oxygen metabolism correlate with this index. The additional DO information could be investigated to evaluate if it can help prevent brain damage due to anesthesia.A cohort of children diagnosed with benign external hydrocephalus undergoing invasive intracranial pressure (ICP) monitoring were monitored during night sleep. This allowed the quantification of the cerebral hemodynamics and metabolism during ICP waves that are indicative of future morbidity in them. This has revealed that ICP waves are associated with hemodynamic and metabolic oscillations. Furthermore, these results have shown that the presence of ICP waves, in particular B-waves, can be observed by DO monitoring which could, in the future, allow their noninvasive assessment in wider populations. An important shortcoming for the routine clinical use of DO has been that the results from commercial NIRS devices on clinical population are not reproducible, often give physiologically invalid results and differ between systems. Apart from the limitations due to the use of continuous-wave light, one major culprit is brain heterogeneity and underlying morphological and functional abnormalities. A comprehensive analysis was carried out using data from different cohorts of brain-injured patients to provide a set of examples and suggestions to establish quality control routines. Hyperventilation is a relatively common therapy, where a decrease in blood carbon-dioxide is induced to cause vasoconstriction in order to lower ICP. Since high ICP often leads to hypoperfusion and hypoxia, this treatment is meant to be beneficial but the findings from clinical practice and large trials provide mixed results. It is hypothesized that this is due to some patients suffering from misery perfusion (MP). Hybrid DO can evaluate whether the therapy causes MP. This was tested in a cohort of patients using advanced statistical methods. The findings indicate that MP is common in these patients and DO can characterize its frequency and magnitude. This paves the way for future clinical-trials to validate the findings and evaluate the efficacy.Other protocols were also carried out as small pilot studies such as during blood transfusion. The results are reported and their potential significance is elucidated. Overall, the versatility of the hybrid DO was demonstrated and new biomarkers were proposed to develop indices that are relevant to the clinicians. These proof-of-principle studies will serve as a backbone for clinical trials and, hopefully in the close future, to the exploitation of this technology in all intensive care units.

• VENTURINI, VALERIA: Mechanisms and functions of the nucleus as a mechano-controller of cell contractility and migration plasticity
Author: VENTURINI, VALERIA
Programme: DOCTORAL DEGREE IN PHOTONICS
Department: Institute of Photonic Sciences (ICFO)
Mode: Normal
Thesis director: WIESER, STEFAN | RUPRECHT, VERENA

Committee:
PRESIDENT: ROCA-CUSACHS SOULERE, PERE
SECRETARI: LOZA ALVAREZ, PABLO
VOCAL: RENKAWITZ, JÖRG
Thesis abstract: Living tissues are crowded and dynamic environments, in which signalling molecules and physical forces constantly act on single cells. To ensure correct tissue development and homeostasis, cells function like small processors: they measure and integrate the various mechano-chemical inputs they receive from their surrounding. As an output, cells translate this information into specific signalling pathways controlling their behavior, cell specification or their physical properties, among others. %Cells can detect changes in chemicals and signalling molecules thanks to specific receptors on their surface, and the associated signalling cascades have been well characterized. In particular, as tissues are built, when external stresses are applied, or when cells rearrange and move, single cells can undergo dynamic shape deformations. Previous studies showed that large cell deformations in confined environments control cellular contractility by tuning myosin II motor protein activity and can transform various cell types into a novel amoeboid phenotype, termed stable-bleb. Still, how single cells can sense shape changes and, as a consequence, tune myosin II activity and cell behaviour remained unknown.Here, by combining planar micro-confinement assays with live cell fluorescence microscopy and quantitative image analysis, we performed a systematic study to characterize the response of progenitor stem cells derived from zebrafish embryos to mechanical shape deformations. By quantifying cellular contractility levels in various conditions and by interfering with specific signalling pathway, we then aimed to identify the mechano-sensitive mechanism that allows cells to sense and respond to shape changes. We found that cells can measure different degrees of confinement, which accordingly defines their contractility set-point. We discovered that the nucleus, the largest cellular organelle, acts as an intracellular mechano-sensor for large cell shape changes. Nucleus deformation induced an unfolding of the inner nuclear membrane, which controls the activity of cytosolic phospholipase A2 (cPLA2) in the nucleus. When active, cPLA2 triggers the release of arachidonic acid that activates myosin II through the Rho/ROCK pathway. As a result, the nucleus allows single cells to accurately and dynamically sense shape deformations and controls cellular contractility and migration plasticity under external force load. This process, further equips cells with an "escape reflex mechanism" that allows migration away from confined environments. Moreover, the combination of inner nuclear membrane unfolding and intracellular nucleus positioning, allows cells to sense and distinguish different shape deformations, as anisotropic cell compression versus isotropic swelling, through the same mechano-sensitive pathway. Our data support that the nucleus establishes a functional module for cellular mechano-transduction, enabling cells to sense and interpret different types of shape changes and to dynamically adapt their behavior to mechanical forces in the 3D microenvironment.

Last update: 06/10/2022 05:01:04.

## Theses related publications

AUTHOR:JULIÀ FARRÉ, SERGI
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Director:LEWENSTEIN, MACIEJ
Co-director:DAUPHIN, ALEXANDRE
Mention:No mention
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AUTHOR:ELU ETXANO, UGAITZ
Title:High-peak-power mid-infrared OPCPAs for extreme nonlinear photonics
Director:BIEGERT, JENS
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Publication date: 15/02/2022
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Publication date: 20/09/2017
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Infrared electric field sampled frequency comb spectroscopy
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Optics letters, ISSN: 0146-9592 (JCR Impact Factor-2020: 7.0
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Seven-octave high-brightness and carrier-envelope-phase-stable light source
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44 µJ, 160 kHz, few-cycle mid-IR OPCPA with chirp reversal
2016 Conference on Lasers and Electro-Optics
Presentation date: 05/06/2016
Presentation of work at congresses

Single-cycle, 9.6-W, mid-IR pulses via soliton selfcompression from a 21-W OPCPA at 3.25 µm and 160 kHz
Presentation date: 01/10/2017
Presentation of work at congresses

260-mJ Ho:YLF pump for a 7-µm OPCPA
High Intensity Lasers and High Field 2018
Presentation date: 27/03/2018
Presentation of work at congresses

Single-cycle, high-power, mid-IR optical parametric chirped amplifier
Mid-Infrared Coherent Sources
Presentation date: 26/03/2018
Presentation of work at congresses

Direct electric-field sampled infrared spectroscopy from 3--25 µm
Conference on Lasers and Electro
Presentation date: 13/05/2018
Presentation of work at congresses

Towards a CEP-stable 10-mJ-level mid-IR OPCPA at 7 µm
Conference on Lasers & Electro-Optics/ European Quantum Electronics Conference 2019
Presentation date: 23/06/2019
Presentation of work at congresses

340 - 40,000 nm coherent light source
2021 IEEE Photonics Conference
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AUTHOR:DESHMUKH, CHETAN
Title:Detection of a single erbium ion in a nanoparticle
Director:DE RIEDMATTEN, HUGUES
Mention:No mention
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Dynamic control of Purcell enhanced emission of erbium ions in nanoparticles
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AUTHOR:FRÖLIAN, ANIKA
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Director:TARRUELL, LETICIA
Mention:No mention
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Interaction Control and Bright Solitons in Coherently Coupled Bose-Einstein Condensates
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Self-bound states in coherently coupled Bose-Einstein condensates
Half Day meeting Barcelona
Presentation date: 08/02/2019
Presentation of work at congresses

Coherent coupling in Bose-Einstein condensates: Interaction control and density dependent gauge fields
Young Atomic Optician conference
Presentation date: 29/07/2019
Presentation of work at congresses

Coherently coupled Bose-Einstein condensates with tunable interactions
ICFO-Hamburg workshop
Presentation date: 04/11/2019
Presentation of work at congresses

Chiral interactions and density dependent gauge fields with ultracold atoms
FOR 2414 student workshop
Presentation date: 04/09/2020
Presentation of work at congresses

AUTHOR:VENTURINI, VALERIA
Title:Mechanisms and functions of the nucleus as a mechano-controller of cell contractility and migration plasticity
Tutor/a:SEWELL, ROBERT
Director:WIESER, STEFAN
Co-director:RUPRECHT, VERENA
Mention:No mention
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Direct force measurements of subcellular mechanics in confinement using optical tweezers
Català, F.; Venturini, V.; Ruprecht, Verena; Krieg, Michael
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How do Cells Sense Physical Forces? Cellular Mechanosensing and Motility in Biomimetic 3D Environments
Joint 12th EBSA – 10th ICBP-IUPAP BIOPHYSICS CONGRESS
Presentation date: 07/2019
Presentation of work at congresses

AUTHOR:SUKEERT, SUKEERT
Title:Versatile nonlinear frequency conversion sources in the near- and mid-infrared
Mention:No mention
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Widely tunable room-temperature continuous-wave optical parametric oscillator based on periodically-poled KTiOPO4
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Green-pumped optical parametric oscillator based on fan-out grating periodically-poled MgO-doped congruent LiTaO3
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Widely tunable, green -pumped, visible and near-infrared continuous-wave optical parametric oscillator based on fan-out-grating PPKTP
8th EPS-QEOD Europhoton conference
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Green-pumped optical parametric oscillator based on fan-out-grating periodically-poled Mg-doped congruent LiTaO3
2019 Conference on Lasers & Electro-Optics/Europe and the European Quantum Electronics Conference
Presentation date: 27/06/2019
Presentation of work at congresses

Green-pumped optical parametric oscillator based on fanout-grating periodically-poled Mg-doped congruent LiTaO3
2019 IEEE Photonics Conference
Presentation date: 02/10/2019
Presentation of work at congresses

Rapidly tunable continuous-wave green-pumped optical parametric oscillator based on fanout MgO:PPLN
2020 Conference on Lasers and Electro-Optics: Science and Innovation
Presentation date: 12/05/2020
Presentation of work at congresses

Continuous-wave green-pumped optical parametric oscillator based on fanout MgO:PPLN
2020 IEEE Photonics Conference
Presentation date: 29/09/2020
Presentation of work at congresses

High-Power Fiber-Pumped Continuous-Wave Difference-Frequency-Generation at 2.26 µm
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Presentation date: 25/06/2021
Presentation of work at congresses

Continuous-wave high-power fiber-based difference-frequency-generation at 2.26 µm
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Presentation date: 18/10/2021
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AUTHOR:KEARY, SARAH
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Director:GARCÍA PARAJO, MARÍA
Co-director:CAMPELO AUBARELL, FELIX
Mention:International Mention
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Presentation date: 26/10/2016
Presentation of work at congresses

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CEWQO - Central European Workshop in Quantum Optics
Presentation date: 23/05/2018
Presentation of work at congresses

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ICAP - International Conference in Atomic Physics
Presentation date: 07/2018
Presentation of work at congresses

POSTER - A versatile neutral-atom microtrap to study light-matter interaction at the single particle level
Quantum Optics ix
Presentation date: 10/2018
Presentation of work at congresses

ORAL - A versatile neutral-atom microtrap to study light-matter interaction at the single particle level
Advances in Quantum Simulation With Ultracold Atoms
Presentation date: 11/2018
Presentation of work at congresses

ORAL - Quantum jump spectroscopy: how to interrogate a single atom
Cold Atoms Meeting
Presentation date: 10/2020
Presentation of work at congresses

AUTHOR:ÖZDEMIR, ONUR
Title:Further Into the Infrared With Quantum Dot Photodetectors
Director:KONSTANTATOS, GERASIMOS
Mention:No mention
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Mid- and long-wave infrared optoelectronics via intraband transitions in PbS Colloidal Quantum Dots
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Size- and temperature-dependent intraband optical properties of heavily n-doped PbS colloidal quantum dot solid-state films
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Single-exciton gain and stimulated emission across the infrared telecom band from robust heavily doped PbS colloidal quantum dots
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Nano letters, ISSN: 1530-6984 (JCR Impact Factor-2020: 11.189; Quartil: Q1)
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Hybrid 2D-QD MoS2–PbSe quantum dot broadband photodetectors with high-sensitivity and room-temperature operation at 2.5 µm
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Intraband Mid and Long Wave Infrared PbS Colloidal Quantum Dot Photodetectors Enabled by Robust Heavy Doping
MRS Fall Meetings and Exhibits 2019
Presentation date: 04/06/2019
Presentation of work at congresses

AUTHOR:PÉREZ SALINAS, DANIEL
Title:Inhomogeneity and disorder in ultrafast phase transitions
Director:WALL, SIMON ELLIOT
Mention:No mention
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Nano letters, ISSN: 1530-6984 (JCR Impact Factor-2019: 20.5
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Study of second and third harmonic generation from an indium tin oxide nanolayer: Influence of nonlocal effects and hot electrons
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Quantitative hyperspectral coherent diffractive imaging spectroscopy of a solid-state phase transition in vanadium dioxide
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Science advances, ISSN: 2375-2548 (JCR Impact Factor-2019: 25.2
Publication date: 13/08/2021
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Second harmonic generation from an ITO nanolayer: experiment versus theory
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Presentation date: 01/04/2020
Presentation of work at congresses

AUTHOR:CASTILLA GÓMEZ, MANUEL SEBASTIÁN
Title:Photodetectors based on graphene pn-junctions for mid-infrared and terahertz range
Director:KOPPENS, FRANK
Mention:No mention
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Nonequilibrium properties of graphene probed by superconducting tunnel spectroscopy
Castilla, S.
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Fast and Sensitive Terahertz Detection Using an Antenna-Integrated Graphene pn Junction
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Journal article

Plasmonic antenna coupling to hyperbolic phonon-polaritons for sensitive and fast mid-infrared photodetection with graphene
Castilla, S.; Vangelidis, I.; Pusapati, V.; Autore, M.; Slipchenko, T.; Rajendran, K.; Kim, S.; Watanabe, K.; Taniguchi, T.; Martín-Moreno, L.; Englund, D.; Tielrooij, Klaas-jan; Hillenbrand, Rainer; Lidorikis, E.; Koppens, F.
Nature communications, ISSN: 2041-1723 (JCR Impact Factor-2020: 14.919; Quartil: Q1)
Publication date: 12/2020
Journal article

Plasmonics of supported nanoparticles reveals adhesion at the nanoscale: implications for metals on dielectrics
Lazzari, R.; Castilla, S.
ACS Applied Nano Materials, ISSN: 2574-0970 (JCR Impact Factor-2020: 5.097; Quartil: Q2)
Publication date: 24/12/2020
Journal article

Highly sensitive, ultrafast photo-thermoelectric graphene THz detector
43rd International Conference on Infrared Millimeter and Terahertz Waves
Presentation date: 09/09/2018
Presentation of work at congresses

Bound in the continuum modes in indirectly-patterned hyperbolic media
2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference
Presentation date: 21/06/2021
Presentation of work at congresses

AUTHOR:PRAKASH, VINDHIYA
Title:NARROWBAND PHOTON PAIRS FOR ATOMS: HIGH RESOLUTION SPECTRAL ENGINEERING AND CHARACTERISATION
Director:MITCHELL, MORGAN
Mention:No mention
RELATED PUBLICATIONS
Autoheterodyne characterization of narrow-band photon pairs
Prakash, V.; Sierant, A.; Mitchell, M.W.
Physical review letters, ISSN: 0031-9007 (JCR Impact Factor-2019: 15.6
Publication date: 19/07/2021
Journal article

A system to interact entangled photon pairs with individual atoms.
Quantum Optics Conference 2018
Presentation date: 01/03/2018
Presentation of work at congresses

Exploring Two Photon Processes Mediated by an Atom
International Conference on Atomic Physics
Presentation date: 25/07/2018
Presentation of work at congresses

CORRELATED PHOTON PAIRS WITH INDEPENDENT FREQUENCY TUNEABILITY FOR COLD ATOM EXPERIMENTS.
Quantum 2019
Presentation date: 27/05/2019
Presentation of work at congresses

Tuneable, Narrowband, Entangled Photons interfaced with Atomic Systems
Conference on Lasers & Electro-Optics / European Quantum Electronics Conference 2019
Presentation date: 24/06/2019
Presentation of work at congresses

Correlated Photons with Independent Frequency Tuneability for Cold Atom Experiments
Young Atom Opticians conference
Presentation date: 29/07/2019
Presentation of work at congresses

A versatile system to study light matter interactions at the level of single quanta
Barcelona Cold Atoms Workshop
Presentation date: 06/02/2020
Presentation of work at congresses

Narrowband Photon Pairs with Independent Frequency Tuneability for Cold Atom Experiments
7th Annual Bristol Quantum Information Technologies Workshop
Presentation date: 27/04/2020
Presentation of work at congresses

HOM interference between distinguishable photons?
8th Annual Bristol Quantum Information Technologies Workshop
Presentation date: 27/04/2021
Presentation of work at congresses

Tricks with atom-resonant quantum light: tailored photons and squeezed-light-enhanced atomic magnetometry.
Workshop on Quantum Interaction of Distant Objects & Applications of Optically Connected Atoms and Nanoparticles
Presentation date: 22/10/2021
Presentation of work at congresses

AUTHOR:MORENO MENCÍA, DAVID
Title:The application of broadband ultrafast spectroscopy to reveal structural, magnetic and electronic dynamics in quantum materials.
Director:WALL, SIMON ELLIOT
Mention:No mention
RELATED PUBLICATIONS
Non-equilibrium dynamics of the prototypical Mott insulator V2O3
ICFOday poster competition
Presentation date: 12/2018
Presentation of work at congresses

Disentangling electron and phonon dynamics in Mott insulating Sr3Ir2O7
ICFOday poster competition
Presentation date: 12/2019
Presentation of work at congresses

AUTHOR:MARTÍNEZ-DENEGRI SÁNCHEZ, GUILLERMO
Title:LIGHT HARVESTING AND ENERGY EFFICIENCY IN PEROVSKITE SOLAR CELLS AND THEIR APPLICATIONS
Director:MARTORELL PENA, JORDI
Mention:No mention
RELATED PUBLICATIONS
Relation between Fluorescence Quantum Yield and Open-Circuit Voltage in Complete Perovskite Solar Cells
Kramarenko, M.; Ferreira, C.; Martínez-denegrí, G.; Sansierra, C.; Toudert, J.; Martorell, J.
Solar RRL, ISSN: 2367-198X (JCR Impact Factor-2020: 8.582; Quartil: Q1)
Publication date: 04/2020
Journal article

Stabilization of the J-V characteristic of a perovskite solar cell using an intelligent control loop
Bheesayagari, C.; Martínez-denegrí, G.; Orpella, A.; Pons, J.; Bermejo, S.; Alcubilla, R.; Martorell, J.; Dominguez, M.
Electronics (Switzerland), ISSN: 2079-9292 (JCR Impact Factor-2020: 2.397; Quartil: Q3)
Publication date: 02/01/2021
Journal article

AUTHOR:GÓMEZ KABELKA, PAU
Title:Spinor Bose-Einstein Comagnetometer and Interhyperfine Interactions in Rb87
Director:MITCHELL, MORGAN
Mention:No mention
RELATED PUBLICATIONS
Interferometric measurement of interhyperfine scattering lengths in $Rb87$
Mazzinghi, C.; Gómez, P.; Martin, F.; Coop, S.; Palacios, S.; Mitchell, M.W.
Physical review A, ISSN: 2469-9926 (JCR Impact Factor-2020: 3.14; Quartil: Q2)
Publication date: 10/09/2019
Journal article

Bose-Einstein condensate comagnetometer
Mazzinghi, C.; Gómez, P.; Martin, F.; Benedicto, D.; Palacios, S.; Mitchell, M.W.
Physical review letters, ISSN: 0031-9007 (JCR Impact Factor-2020: 9.161; Quartil: Q1)
Publication date: 29/04/2020
Journal article

Cavity-enhanced polarization rotation measurements for low-disturbance probing of atoms
Mazzinghi, C.; Benedicto, D.; Gómez, P.; Lucivero, V. G.; Aybar, E.; Gugnani, S.; Mitchell, M.W.
Optics express, ISSN: 1094-4087 (JCR Impact Factor-2020: 3.894; Quartil: Q1)
Publication date: 06/12/2021
Journal article

Single-domain Bose condensate magnetometer achieves energy resolution per bandwidth below h
Coop, S.; Palacios, S.; Gómez, P.; Zamora-Zamora, R.; Mazzinghi, C.; Mitchell, M.W.
Proceedings of the National Academy of Sciences of the United States of America, ISSN: 0027-8424 (JCR Impact Factor-2020: 11.205; Quartil: Q1)
Publication date: 08/02/2022
Journal article

AUTHOR:MUÑOZ GIL, GORKA
Title:Anomalous diffusion: from life to machines
Director:LEWENSTEIN, MACIEJ
Co-director:GARCÍA MARCH, MIGUEL ANGEL
Mention:No mention
RELATED PUBLICATIONS
Restricted Boltzmann machines as variational wave functions
Annual Barcelona cold atom meeting 2020
Presentation date: 06/02/2020
Presentation of work at congresses

Certificates of many-body quantum properties assisted by machine learning
Quantum techniques in machine learning
Presentation date: 11/11/2020
Presentation of work at congresses

AUTHOR:HANCU, ION MICHAEL
Title:Controlling the multipolar interference of nanoantennas
Director:VAN HULST, NIEK
Mention:No mention
RELATED PUBLICATIONS
Selective excitation of individual nanoantennas by pure spectral phase control in the ultrafast coherent regime
Accanto, N.; De Roque, P.; Galvan-Sosa, M.; Hancu, I.; Van Hulst, N.
Nanophotonics, ISSN: 2192-8614 (JCR Impact Factor-2020: 8.449; Quartil: Q1)
Publication date: 07/09/2020
Journal article

## Research projects

START DATEEND DATEACTIVITYFINANCING ENTITY
30/11/202130/11/2021Self-Referenced Sensor
15/09/202115/09/2021Light sheet-based imaging device with extended depth of field
16/02/202116/02/2021Dispositivo fotovoltaico con un conjunto de fibras para seguimiento del sol
01/01/201930/09/2022NUEVOS EFECTOS EN PLATAFORMAS DE GUIAS DE ONDA ANISOTROPASAgencia Estatal de Investigación
01/01/201731/12/2021ICREA ACADEMIA 2016-04INSTITUCIO CAT DE RECERCA I
01/01/201730/09/20212017 SGR 1400 Nonlinear and Quantum Photonics GroupAGAUR. Agència de Gestió d'Ajuts Universitaris i de Recerca

# Teaching staff and research groups

UPC groups:

## Research projects

START DATEEND DATEACTIVITYFINANCING ENTITY
30/11/202130/11/2021Self-Referenced Sensor
15/09/202115/09/2021Light sheet-based imaging device with extended depth of field
16/02/202116/02/2021Dispositivo fotovoltaico con un conjunto de fibras para seguimiento del sol
01/01/201930/09/2022NUEVOS EFECTOS EN PLATAFORMAS DE GUIAS DE ONDA ANISOTROPASAgencia Estatal de Investigación
01/01/201731/12/2021ICREA ACADEMIA 2016-04INSTITUCIO CAT DE RECERCA I
01/01/201730/09/20212017 SGR 1400 Nonlinear and Quantum Photonics GroupAGAUR. Agència de Gestió d'Ajuts Universitaris i de Recerca

# Quality

The Validation, Monitoring, Modification and Accreditation Framework (VSMA Framework) for official degrees ties the quality assurance processes (validation, monitoring, modification and accreditation) carried out over the lifetime of a course to two objectives—the goal of establishing coherent links between these processes, and that of achieving greater efficiency in their management—all with the overarching aim of improving programmes.

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