Casimir Research School Delft – Leiden Report 2012

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Casimir Research School Delft-Leiden

Report 2012

Content

Casimir in 2012 5 1. Scope of the Casimir Research School 7

1.1. The school´s core business 1.2. Description of the research themes 1.3. Educational activities 1.4. Organization

2. Students and Staff 15 2.1. PhD students 2.2. Recruitment and job market

2.3. New PhD cohort 2012 2.4. Staff developments

3. Education 21 3.1. Overview of Casimir courses 2012 3.2. Arnemuiden

4. Research News 25

4.1. Timeline of research highlights 2012 4.2. Casimir theses 2012

5. Outlook to 2013 33

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Casimir in 2012

In 2011 the Dutch Ministry of Education launched a new call for proposals under the name “Zwaartekracht” for scientific consortia with a potential to become internationally leading centers of excellence. In this first round a total budget of 167M€ was available for funding over a total period of ten years. Dutch universities were invited to submit a maximum of four proposals in all areas of academic study. Casimir submitted a proposal under the title “Frontiers of Nanoscience” (NanoFront), and participated in a proposal by the Delta Institute for Theoretical Physics on “Matter at all Scales”, jointly with the universities in Amsterdam and Utrecht. In November 2012 we learned that out of a total of 42 proposals six programs were awarded. We are very proud that both Casimir programs were awarded, by which practically all research in Casimir is covered by Zwaartekracht funding.

The NanoFront consortium was led by Cees Dekker, together with Carlo Beenakker, Joost Frenken, Hennie Zandbergen, Leo Kouwenhoven, and Michel Orrit. The program brings together all research in nanoscience of the groups at the Kavli Institute in Delft with the research groups in experimental and theoretical nanoscience in Leiden, with a total of 61 research staff. The program is subdivided into three research themes: Frontiers of quantum nanoscience, Frontiers of bionanoscience, and Frontiers of Nanotechnology. The budget awarded for the 10 year duration of the program totals 35.9M€. In addition, the boards of the universities at Leiden and Delft have supported the application with an investment budget of 15M€.

The consortium on theoretical physics “Matter at all Scales” was led by Erik Verlinde (Univ. of Amsterdam), together with Gerard ’t Hooft (Utrecht), Jan Zaanen (Leiden), Carlo Beenakker (Leiden), Henk Stoof (Utrecht), and Jan de Boer (Amsterdam). It brings together research in problems as diverse as complex electron systems, quantum devices, and cosmology. These are unified by a common mathematical toolbox, which has been a successful concept in the organization of the Institute Lorentz at Leiden for many years. The budget awarded for the 10 year duration equals 18.3M€.

These two programs will permit starting new research directions within Casimir by the hiring of new talent. There will be ample room for investment so that we can support starting research staff with a suitable start-up budget. It will further permit upgrading the experimental infrastructure, and flexibility in initiating new research directions for existing groups.

Against the general trend of decreasing research budgets 2012 has been an exceptional year for Casimir. Many individuals won prestigious grants and prizes, where it deserves to name particularly the ERC Synergy Grant awarded to Leo Kouwenhoven, Carlo Beenakker en Lieven Vandersypen.

This team has also been responsible for one of the most remarkable scientific discoveries of 2012: the detection of a collective electron state that can be described as a Majorana fermion. It is expected that this discovery will form the start of a new exciting direction in the quest for quantum computation.

The Casimir Research School has seen important changes in its organization. The daily coordination of the school was in the hands of Maddy Lansbergen, who has

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now left us to join the office of the Delft Graduate School. Meanwhile, we found an excellent new coordinator for the School in the person of Marije Boonstra.

The recruitment of talent for our MSc and PhD programs was given more visibility through the “Join in his/her footsteps” advertisement campaign and a newly-designed website. The first results are promising, and we have been able to attract a number of excellent young people to the PhD program. For the MSc program we have not yet reached the target population. The coming year, both the advertisement campaign and selection procedure will be further refined.

In 2012 a total of 52 new PhD students joined Casimir, and the number of completed and defended theses is 39. Both are record high numbers in the young history of the Casimir Research School. We note that the average time-to-thesis for PhDs awarded in 2012 increased compared to preceding years, likely due to the fact that we have succeeded in bringing a number of late theses to completion. We expect that the average time-to-thesis will descend again to the target of close to four years in the coming years, and we will maintain this as one of our important targets.

A new edition of the Casimir Spring School, this year held in Arnemuiden, again proved the success of its concept. The program is fully in the hands of the PhD students and the meeting is only attended by PhD students and postdocs. The fact that no senior staff is present at the meeting places the young people in control of the discussions and is a great stimulus for scientific interactions and networking.

We are happy to look back on a very successful year for the Casimir Research School. The year 2012 has brought many positive changes and we have many reasons to be optimistic about the future of our school.

Prof.dr. Jan M. van Ruitenbeek

Prof.dr. Nynke H. Dekker

July 2013

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1. Scope of the Casimir Research School

1.1. The school’s core business Casimir Research School – Casimir, in short – is a graduate school in interdisciplinary physics, jointly operated between Leiden University and Delft University of Technology in the Netherlands. The research and the MsC- and PhD-training programs are executed by groups at the Kavli Institute of Nanoscience in Delft (KAVLI) and at the Leiden Institute of Physics (LION). The school was established in 2004 and accredited by the Royal Dutch Academy of Arts and Sciences (KNAW) in 2005. In 2009, Casimir was the highest-ranked recipient in the first round of the Graduate Program fund through which the Netherlands Organization for Scientific Research (NWO) stimulates innovations in research training. The Casimir Research School performs research in the area of interdisciplinary physics, covering six domains, all across the sectors of theoretical, experimental and applied research as well as industrial research, as illustrated in table 1.

Casimir research themes

Associated disciplines Theory Experi- ment Applied Industrial

1. Molecular biophysics Biological, Medical and Pharmaceutical Sciences

++ +++++ ++++ ++++

2. Physics of nanostructures

Electrical Engineering; Chemistry; Biology

+++++ ++++ +++

++++ ++

+

3. Quantum matter and functional materials

Chemistry; Material Sciences

++ ++++ + +

4. Quantum information and quantum optics

Informatics; Material Sciences

+ ++++ + +

5. Universe physics Astronomy; Mechanical Engineering

++++ ++++ + +

6. Dynamic complex systems

Chemistry; Biology; Mechanical Engineering; Materials Sciences

+++ ++ +

Table 1. Overview of research themes in interdisciplinary physics covered by Casimir. The number of research groups active in each sector and in each theme is indicated by a corresponding number of +’s. Some of the industrial partners in research are given in the right column. The Casimir Research School aims at integrating the full scope of research activities, from basic research in theoretical and experimental physics, through applied physics and industrial research. We have the ambition of achieving breakthroughs in our understanding of nature, in pushing the frontiers of experimental techniques, in opening new application perspectives, and in breaking down barriers for improved products and processes in industry. The cross-fertilization of the approaches and people working in the different ‘flavours’ of research is seen as being essential for achieving breakthroughs. The Casimir Research School facilitates optimal interaction between the three approaches, often mixing them on the research-group level. In terms of our current scientific publications, the school’s scientific output mixes high-profile fundamental results (in journals such as Physical Review Letters), results of a widely attractive nature (Nature, Science) and patents. Research collaborations are forged equally with leading universities worldwide, as well as with institutes of technology and industrial partners. While theory, experiment, and applied research can be found largely in house, most of our industrial research takes place through ties with private sector partners. These

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ties are maintained in several ways. Researchers with an appointment at selected private sector partners have part-time professorship appointments at our universities (indicated in table 1). Such part-time professors will be teaching one or more courses and (co-)supervise PhD research projects at the universities, or at the site of the private sector partner. This is a very effective means of bringing students, PhD students, and staff in close contact with developments in industry and creating awareness of the needs and constraints within the industry. Industrial partners are also involved through co-funding of research and by jointly operated research programs, by sponsoring of targeted research areas and contract research, and as spin-out companies of research projects. Research at the Casimir Research School is focussed on research-themes in physics that interact strongly with developments and skills in other disciplines (interdisciplinary physics). This focus is motivated from the fact that many of the exciting new developments in research take place at the boundaries between disciplines. Moreover, for students the skills acquired in communicating with other disciplines are very valuable for any future career. Thus, most of the individual research projects executed by Casimir researchers are interdisciplinary projects, executed in close collaboration with biologists, chemists, material scientists, etc. In table 1 we list the dominant associated disciplines for each Casimir theme. Research and training are inseparable activities at the school. This means that staff members teach all courses in the MSc and PhD programs and that all education is research-oriented, incorporating the latest research insights. Each PhD student performs an independent research project as full member of one or more research groups, with Casimir providing additional cross-links between groups and to outside stakeholders such as potential employers or industrial research groups. Casimir has been a driving force in further strengthening of the ties between research and education programs in Leiden and Delft. This has resulted in the formulation of joint proposals for Leiden and Delft in the recent national investment programs known as the “Sectorplan”, and the NWO program “Gravity”. Similar signs of strength in combining complementary programs have led to intensified collaboration between the universities of Leiden, Delft and Rotterdam, as recently publicly announced. The Casimir Research School is building a European network of research schools together with the Université Joseph Fourier in Grenoble, France, the Karlsruhe Institute of Technology and Ludwig Maximillian Universität München. With these four partners Casimir co-organizes the yearly summer school in Les Houches.

1.2. Description of the research themes A complete overview of all research activities in Casimir is beyond the scope of this brief overview. In order to provide a picture of the activities in the six research themes some of the highlights of current research directions are given here. Research Theme 1 – Molecular Biophysics Cells are comprised of a multitude of molecular components that must work together to perform an impressive array of complex tasks. How these components function together to comprise a living system is a question of fundamental interest. Studying the workings of a living cell can greatly benefit from a physics-based, quantitative approach, e.g. optical microscopy, nanotechnology at the scale of the cell’s molecular components, etc. Such an approach must be integrated within the context of broad expertise: a new Department of Bionanoscience, led by Prof. Cees Dekker, has recently been established at Delft and is already growing into a strongly multidisciplinary team of scientists with varying backgrounds ranging from cell

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biology, molecular biology and biochemistry, synthetic biology, theoretical biology to biophysics, high-resolution microscopy, nanomedicine, nanoprobes and bionanoapplications. The research generally aims at understanding the molecular processes in a cell. Examples of important research goals are: understanding the mechanism of replication and repair of DNA by in-vitro single-molecule techniques, understanding how multi-protein complexes function as a whole, or studies of the mechanism by which bacteria acquire resistance against antibiotics. In the last two decades, biophysical research has led to important breakthroughs by making it possible to study biomolecules and biopolymers at the single-molecule level. This has provided a lot of fundamental insight and understanding of the physical properties of these molecular objects. However, these studies are mostly based on idealized in-vitro experiments, and it is expected that the processes in real living cells will be qualitatively and quantitatively different. The challenge in the field in the coming years will be to take the research to next level and study these processes in the more realistic environment of living cells. To make this possible, physicists, together with chemists and biologists, will need to develop noninvasive tools. One example of an approach under study involves gold nanoparticles. As demonstrated recently by the group of Orrit, it is possible to image the light scattering of single gold nanoparticles. The particles are non-toxic and do not suffer from photo-bleaching. Through collaboration between the groups of Orrit, Van Noort and Schmidt (Leiden) these particles will be used as labels for probing single molecule dynamics in a living cell. In addition they will be used for quantifying the local mechanical properties in the cell, by applying forces through optical tweezers. Research Theme 2 – Physics of Nanostructures Its many exceptional properties have attracted several groups to start research on physics and applications of graphene. These include the groups of Aarts, Beenakker, and Frenken in Leiden, and Vandersypen, Zandbergen, and Dekker in Delft. Regarding its electronic properties, device applications could profit from an exceptionally high mobility allowing ballistic electron device architectures. In practice the mobility is still limited by the presence of impurities. Important progress has been made in increasing the mobility by various techniques. One of the goals will be to directly demonstrate Klein tunneling, for which the transmission probability of a tunnel barrier is expected to depend on the angle of incidence. In parallel, work on quantum dots defined in graphene is related to the effort on quantum computation. A single electron spin trapped in a graphene quantum dot is expected to have a long life time because of small spin-orbit scattering and the small number of nuclear spins. Graphene will also be used for contacting of individual organic molecules. More generally, by various techniques it has become possible to apply electrical leads to individual organic molecules, and to probe their electronic transport properties. Organic molecules form stable entities at the nanoscale, while the quantum transport properties can be controlled through design of the compound, which opens perspectives for a range of applications. Some of the most important techniques used in these studies have originated from Casimir research groups, notably the mechanically controllable break junction (MCBJ) technique, while improved techniques were developed for electromigration break junctions and 2D molecule/nanoparticle networks. Research in the groups of Van Ruitenbeek and Van der Molen (Leiden) and Van der Zant (Delft) will focus on interference effects of multiple current paths in the molecules, which lead to sharp resonances. Such phenomena may be relevant for efficient thermoelectric energy conversion. Another

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line of research will search for non-conservative forces due to the current, which would allow electrically driven motion at the nanoscale. Scanning-probe microscopy has become a most versatile and broadly applicable type of instrument in nanoscience. One type of such scanning probes, magnetic resonance force microscopy (MRFM), measures local magnetic forces in combination with magnetic force due to a single electron spin can be detected. Still, the limit to sensitivity has not yet been reached. The goal is to be able to measure the force of a single nuclear spin. Once this is possible, the method can be used for mapping the 3D distribution of nuclear spins in a molecule. Analogous to Magnetic Resonance Imaging now in routine use in hospitals for 3D imaging of patients, the MRFM would open the way to 3D imaging of single proteins at the nanoscale. Knowing protein structure is of central importance to understanding its function. Oosterkamp and his group in Leiden have taken important steps towards reaching the required sensitivity. Improvements include lowering the temperature into the milliKelvin regime, increasing the field gradients by the use of magnetic nanoparticles, nanofabrication of the force sensor, and employing detection techniques using SQUIDs rather than laser interferometry. Research Theme 3 – Quantum Matter and Functional Materials The development of more efficient catalysts for industrial chemical reactions is one of the most economically relevant research goals. Yet, progress has been slow because we do not have the tools for analyzing exactly what happens at the atomic scale on a catalyst’s surface. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have been widely used for studying chemical reactions at surfaces. However, most studies are done under highly idealized conditions (low pressures, flat surfaces, etc.) with limited relevance for real catalysts. The group of Frenken (Leiden) has recently developed new STM and AFM instruments that permit working under “industrial” conditions, while the actual chemical processes are taking place. This has led to many joint projects with industrial partners in catalysis, such as Albemarle, Haldor Topsøe, and Shell. The STM instrument itself is now being offered commercially through a spin-off company, Leiden Probe Microscopy. The research has already produced new insight into the active processes involved in some of the most widely used catalysts. The resolution in the images has not yet reached the atomic scale but current research should bring this goal within reach, which will allow monitoring individual reactions and associating the reactions with specific sites. At the same time, in collaboration with industry, many commercial catalysts will be studied for improved understanding of their function, and avenues towards improved materials will be explored. Research Theme 4 – Quantum Information and quantum optics Quantum computation has captured the imagination of many, but has long seemed beyond reach. More recent developments, with seminal contributions from the groups of Mooij, Kouwenhoven and Vandersypen (Delft) have shown that quantum systems can be used for information storage and manipulation, and many of the main obstacles towards realizing an actual, scalable, design have been removed. Still several important steps remain to be taken, and each problem to be solved requires profound understanding of physics and a lot of creativity. The approach to quantum computation in Casimir is through solid-state nanofabrication of qubits, as this is one of the most promising avenues for scaling up to many qubits, whether in the form of superconducting circuits (DiCarlo), spins in diamond (Hanson), or spins in semiconductor quantum dots (Vandersypen and Kouwenhoven). The central challenge is to maintain quantum coherence for such “large” qubits. Very recently,

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with seminal contributions from Beenakker’s group (Leiden), it has been suggested that information may be stored indefinitely in the form of Majorana Fermions. These could be realised in a solid state device by coupling a so-called topological insulator with a superconductor. The groups of Kouwenhoven and Beenakker are among the principal candidates for reaching this goal, and the first results have recently been published. Equally important is the emission and detection of single photons, as well as the future quantum repeater, all important elements of a future quantum internet, work that is the focus of the Zwiller group. Quantum states are becoming more tangible also because it starts to be possible to observe quantization of mechanical vibration states of macroscopic objects. The groups of Bouwmeester and Oosterkamp (Leiden) and Van der Zant and Steele (Delft) are exploring this territory. A very profound connection with the foundations of quantum mechanics has been made by Penrose. He has argued that an oscillating mass described by quantum mechanics should influence its own motion through the deformation of space-time, as a consequence of general relativity. This means that quantum mechanics as we know it should break down for an oscillator of sufficient mass, oscillating at sufficiently large amplitude. Such oscillators are being developed in Bouwmeester’s team, where the goal is to bring a mechanical oscillator in quantum superposition with a single photon in an optical cavity. The experiment requires a combination of advanced optical techniques, cryogenic techniques down into the micro-Kelvin regime and below, and micro- and nano-instrumentation. Research Theme 5 – Universe physics String theory is one of the dominant approaches for reconciling quantum mechanics and general relativity. It describes the physics at the very largest scale of black holes and cosmology and at the smallest scale of elementary particles. More recently much attention has been drawn to a property known as the AdS/CFT correspondence, by which models in string theory can be mapped onto models in conformal field theory. The interest lies in the fact that conformal field theories are applicable more widely, notably in many-particle systems in condensed matter physics. Through a recent collaboration between the groups of Zaanen and Schalm (Leiden) it was demonstrated that it is possible to use such models for calculating the excitation spectrum of a correlated electron system as a function of external parameters, all the way through a quantum phase transition. In parallel, proposals appeared for describing unconventional “holographic” superconductivity. For many unconventional superconductors, including the cuprate high-Tc superconductors, the actual mechanism for pairing is still unknown, with the mechanism above being one of the prominent candidates. Zaanen’s group has now proposed an experimental avenue for elucidating the actual pairing mechanism by measurement of the pair susceptibility. This may finally resolve one of the most important problems in condensed matter physics. Together with the experimental groups of Van Ruitenbeek, Hilgenkamp, and Aarts (Leiden) the program for the coming year will be to test these predictions. More generally, the AdS/CFT correspondence will be applied for finding condensed matter systems that may be described through models in string theory and for finding models in condensed matter systems that may provide experimental tests of predictions in string theory.

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Research Theme 6 – Dynamic Complex Systems Many physical, biological and socio-economic systems display a high degree of differentiation in their structure and organization. The relations existing among the many underlying units of such systems give rise to a challenging degree of complexity, which is typically reflected in highly nonlinear responses to perturbations, fractal spatial and temporal patterns, nontrivial correlations, intricate networks of interactions, irreducible multi-scale behavior, and spontaneous emergence of collective properties. The groups of Vitelli and Van Hecke (Leiden) investigate a broad range of phenomena in soft materials, with an emphasis on the physics of frustrated and amorphous materials such as granular media, foams, glasses and fibrous networks. The focus is to understand, by means of a combination of theory, experiments and simulations, how soft materials organize, and how this organization impacts their mechanical properties, such as vibrational modes, elasticity, shock waves, flow and failure. A current focus is to understand the dominant role of nonlinearities in soft materials that are brought close to certain critical points, associated with failure, unjamming and marginality. Garlaschelli’s group (Leiden) performs research in Complex Networks theory and Econophysics. The main goal of this research is the development of an information-theoretic approach to the structure and dynamics of large networks, with an emphasis on socio-economic systems where dealing with the multiple-scale nature of interactions is particularly critical. Previous research in the group has shown that it is possible to use the properties of canonical ensembles in statistical mechanics in order to distinguish nontrivial topological patterns from randomness in real complex networks, and also to stochastically reconstruct the structure of networks from partial information. Future goals include extensions of the theory to financial time series and more complicated scenarios. This work is performed in interaction with and co-funded by the company Duyfken Knowledge BV.

1.3. Educational activities

Support of MSc students For students with an interest in a research career beyond the MSc phase, Casimir has established a special pre-PhD track within the existing MSc programmes Physics (in Leiden) and Applied Physics (in Delft). The track is funded by the Dutch Research Council (NWO) through a competitive programme for Graduate schools. This Master’s track focuses on educating students, especially for PhD positions at the two institutions or elsewhere and is designed to respond to the increasing mobility of students after completing their BSc. The track leads to a particular set of courses and research experiences in more than one department. A selection takes place for entrance into this track.

For a limited number of students within this track, a PhD position is guaranteed. This so-called prize-PhD position is co-funded by NWO, TU

Delft and Leiden University independent of specific research funding. Students apply to these positions by writing a research proposal themselves. Other students within the Casimir pre-PhD track will have excellent PhD job prospects. In 2012, Julia Cramer and Christopher Berg Smiet were awarded with Casimir PhD positions.

Julia

Christopher

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The Hendrik Casimir prize winners 2012

Every year, the Casimir Research School awards prizes for the best MSc students. This year’s award winners are Chris Watson (Delft) and Jelmer Wagenaar (Leiden). They received the 2012 Hendrik Casimir prize, in the form of a certificate and a sum of €750,-.

The prize is based on the revenues from a donation by the late Josina Casimir-Jonker, widow of Hendrik Casimir. The selection was made by a committee formed by dr. Jos Thijssen (director of Master Education Delft), prof. Jan Aarts (Director of Education Leiden) and dr. Sander Otte

(coordinator of the Casmir pre-PhD Master program).

The prize winners, Chris Watson and Jelmer Wagenaar, are both excellent MSc students that have been selected because of their exceptional results, in experimental physics as well as in theoretical physics.

Training of PhD students

The Casimir Research School organizes workshops and offers special graduate and advanced graduate courses. Casimir PhD students are required to acquire 15 ECTS credits in thematic graduate education during their PhD. This number is chosen as to allow PhD students to attend at least two graduate courses and several workshops, concentrated mostly in the first years of their PhD project duration. An overview of the program is given in section 3 below. Casimir uses the following formats for its educational activities:

Graduate courses throughout the year Personal development courses One-week Casimir schools The bi-annual Casimir Science days A bi-annual Spring School for PhD students and post-docs only Each PhD student has its own educational plan, detailing the workshops and courses to be attended. The PhD supervisors coach the students in drawing up and updating this plan, and monitor progress in an informal and formal way.

Fully in the spirit of Hendrik Casimir, the research school aims to provide PhD students with more than just training for a specific subfield of physics. Personal development courses are part of the educational programme, too. These courses are offered by the participating universities and the funding agencies FOM and NWO. A full list of courses can be found on the Casimir website. They cover topics such as presentation skills, scientific integrity, time management and business orientation.

Jelmer

Chris

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1.4. Organization In 2012, the Casimir organization consisted of the following persons:

Scientific director Prof. dr. J.M. van Ruitenbeek Co-director Prof. dr. N.H. Dekker

Casimir Board Casimir Education Committee Dr. C. Danelon Dr. C. Danelon Prof. dr. E.R. Eliel Dr. ir. R. Hanson (chairman) Prof. dr. J. Zaanen Prof. dr. T. Oosterkamp Prof. dr. ir. H.S.J. van der Zant Prof. dr. H. Schiessel Coordinators Casimir pre-PhD MSc-track Sander Otte (Delft) Reyer Jochemsen (Leiden) Casimir coordinator Maddy Lansbergen (until December 2012) Casimir PhD platform Jetty van Ginkel (Bionanoscience, Delft) Hedde van Hoorn (Biophysics, Leiden) Vincent van Mourik (Quantum Transport, Delft) Jelmer Renema (Quantum Optics, Leiden) Jan van Ostaay (Theoretical Physics, Leiden, until 31 December 2012) Mickael Perrin (Mol. Electronics & Devices, Delft) Casimir scientific advisory Prof. B. Noordam, Professor of Physics, University of Amsterdam and ASM

Lithography (together with P. Gosling he is the author of “Mastering your PhD; Survival Success in the Doctoral years and beyond”, Springer, Berlin/Heidelberg, 2006) (until 31 December 2012)

Prof. J.P. Kotthaus, Professor of Physics and former Director of the Center for Nanoscience, München, Germany

Prof. M.R. Beasley, Professor of Applied Physics and Electrical Engineering and former Dean of the School of Arts and Sciences, Stanford University, Stanford, USA

Prof. Zheng-Yu Weng, Professor of Theoretical Physics, Tsing-Hua University, Beijing, China

Prof. P.B. Littlewood, Professor of Physics and Director of the Cavendish Laboratory, Cambridge University, Cambridge, UK (from 1 February 2009)

Prof. Jonathan Howard, Max Planck Institute for Molecular Cell Biology & Genetics and Professor of Biophysics, Dresden University of Technology

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2. Students and staff

2.1. PhD students At the end of 2012, 207 PhD students were enlisted in the Casimir Research School. In total, 39 PhD students finished their project in 2012 and published their results in their final theses. This is the highest number of thesis completion since the start of Casimir in 2005.

Staff* Postdocs PhD students Theses PhD Dropout

Leiden: 42 35 88 21 2 Delft: 43 36 119 18 0 Total: 85 71 207 39 2

* Number of Casimir staff members (not FTE) including part-time appointments and retired staff members still active in our research community

Year Theses completed Average time to thesis approval (years)

2005 23 4.54 2006 28

2007 22 4.26 2008 17 4.49 2009 25 4.02 2010 31 4.20 2011 23 4.15 2012 39 4.50*

*excluding two outliers (time to thesis: > 7 years, due to personal circumstances)

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Time to thesis Casimir PhD’s 2012

In 2012, supervisors actively encouraged students that had spent already five years or more to finish their theses. This special effort had a positive effect, but results in over 25% of the theses published in 2012 written in five years or more, while this number lies around 10% when all Casimir theses published since 2001 are included.

0 1 2 3 4 5 6 7 80

20

40

60

80

100

PhD

deg

rees

aw

arde

d (%

)

time-to-thesis (Year)

50 %

4 year 3 months

Casimir p-profile, showing the cumulative numbers of theses completed as a function of the time-to-thesis (the time between start of a PhD studies and the completion acceptance of the manuscript) for all completed PhD’s within Casimir for starting dates since 2001. The median of the distribution (with 50% of all theses completed) falls at 4 years and 3 months.

0

2

4

6

8

10

12

< 3 3‐3,5 3,5‐4 4‐4,5 4,5‐5 5‐5,5 5,5‐6 6‐7 > 7

frequency

n = years

Time to thesisTheses published in 2012 (total = 39)

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2.2. Recruitment and job market Recruitment of PhD students The following steps have been taken: 1. Various PhD positions have been filled with talented young students who

entered Leiden or Delft as MSc students from elsewhere and were selected as candidates for a PhD position within Casimir. The conclusion is that it is very important to continue to provide scholarships for gifted students from elsewhere to enroll for the MSc study.

2. The Casimir-office has used the methodology of uploading applications to a database to enable individual group leaders to bring suitable candidates to the attention of colleagues.

3. An international campaign was started to actively recruit PhD. & MSc. students. Six PhD students in Leiden and Delft were asked to write a testimonial about their personal experiences here. Subsequently, posters were made, each one featuring one of these PhD students with a quote and a picture. The recurring line in the campaign was: ‘join in his footsteps’ or ‘join in her footsteps’. Three quotes were focused on science and three on secondary motives. The posters were sent around the world, using the networks of several PI’s and PhD-candidates. In the fall of 2012, several of the selected PhD students visited their home universities where they presented a seminar on their research work. Furthermore, a website was launched (www.joinourfootsteps.nl) and a deadline was set. Prospective students were invited to apply before 7 January 2013.

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Career perspectives Overall, the career perspectives for our alumni are very good. Casimir keeps track of the first and second jobs of the former PhD’s. The pie chart diagram below provides an overview of first job, based on information provided by those who received their PhD in 2012. Although the economic crisis may prolong the time one has to spend searching for a job, it still seems that for the large majority of our former students a new position has been secured well before, or within a few months after completing the PhD training.

Figure 2. Pie chart showing the initial career steps of the Casimir Research School PhD alumni of 2012.

2.3. New PhD cohort 2012

Statistics Recruitment PhD Students Cohort 2012

Leiden/Delft and Male/Female 2012 Nationality

Total Male Female Dutch Europe (non-Dutch) World (non-Europe) Delft 31 21 10 11 7 13 Leiden 21 17 4 10 7 4 Total 52 38 14 21 14 17

postdoc/academia54%

high‐tech industry13%

consultancy15%

finance5%

self‐employed5%

applying/unknown8%

Career perspectives PhD‐alumni 2012

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2.4. Staff developments Several new young research staff members have joined Casimir in 2012, including:

Dorothea Samtleben has been appointed as a new member of the scientific staff of the Leiden Institute of Physics (LION). Dorothea has her roots in Hamburg where she began her scientific career working as an experimental physicist on collider experiments at the electron proton collider HERA at DESY. A fellowship at the University of Chicago led her into the field of observational cosmology studying the oldest photons in the universe, the Cosmic Microwave Background Radialtion (CMB) She joined CAPMAP, one of the first experiments measuring the faint polarization signal of the CMB which provides insights into the development of the early universe. She continued the path in cosmology then at the Max-Planck-Institut für Radioastronomie in Bonn with the international experiment QUIET that is aiming to address the even fainter polarization pattern in the CMB expected as signature from the inflation of the universe in its first tiny fraction of a second. In addition to data analysis she was responsible for the development of the data acquisition system and receiver components within these CMB experiments. In 2010 Dorothea joined Nikhef in Amsterdam where she embarked on the Antares/Km3NeT neutrino telescope projects that are aiming at opening a new window to the Universe by exploiting neutrinos as messengers from the distant Universe with light detectors installed in the Mediterranean Sea. Alongside her new position at the University of Leiden, Dorothea will also continue researching at Nikhef, thereby establishing a new link between the theoretical and experimental sides of cosmology.

In September 2012, Timon Idema started a new theoretical biophysics group at the Department of Bionanoscience at the TU Delft. From February 2010 until June 2012, he was a postdoc at the University of Pennsylvania in Philadelphia, U.S.A., working on several problems in soft condensed matter theory and theoretical biophysics. Timon is not unfamiliar with Casimir: until December 2009, he worked at the Lorentz Institute of Leiden University on two topics in biophysics: the morphology of membranes and the behaviour of molecular motors.

Dorothea

Timon

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3. Education

3.1. Overview of Casimir courses 2012 Casimir PhD Course “Electronics for Physicists” (fall 2012)

Subject area: The course is a must-have for PhD students and post-docs interested in experimental physics Number of participants: 36 participants passed the final exam and received the Casimir certificate Lecturers: Dr V. Zwiller, R. Schouten Description: We study electronics with a strong focus on practical applications. After reviewing the basics of passive and active components and their practical limitations, we focus on circuit simulation, systematic troubleshooting and opamp circuits. Signals, noise and interference problems (and solutions!) are also an important topic. We finish with an overview of microwaves and various measurement techniques, and a day on advanced use of electronic measurement equipment. Several case studies from the physics lab are used throughout the course to make the theory come alive. Casimir Course “Hot Topics in Quantum NanoScience” Subject area: Exemplary topics are topological insulators, mesoscopic quantum gravity, string theory for condensed matter, measurement-based quantum computing, quantum-limited sensors, Majorana Fermions, fast-light with single photons, etc. Preparation: The tutorial, as a one-hour lecture, is open for everyone to attend. A second hour is reserved as a discussion hour between the registered class of PhD students and postdocs with the lecturer. The course teachers act as moderators. Apart from attending the public lecture, private discussion and reading the research paper, each session is concluded by writing a one-page essay within one week on the subject and preferentially in the context of the participant’s own research. Number of participants: 20 Hosts: Gary Steele, Leo DiCarlo, Leo Kouwenhoven and Tjerk Oosterkamp Description: Speakers from all over the world will be asked to present pedagogical introductions to their field with an emphasis on basic concepts. Besides such an introductory lecture open for everybody, the participants of this course will have an additional discussion with the speaker discussing a recent paper and the holy grails of the field.

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The 2012-2014 Casimir course scheme: Course Lecturers Dates Location GSC Hot Topics in Quantum Nanoscience

L. Kouwenhoven G. Steele L. Di Carlo T. Oosterkamp

Ongoing course 10 per year

Delft / Leiden 5

Electronics for Physicists

V. Zwiller, R. Schouten

Fall 2012 Leiden / Delft 5

Frontiers of measurement

M. Orrit, T. Oosterkamp, G. Steele

to be announced Leiden / Delft 5

Biology for Physicists

M.-E. Aubin-Tam B. Beaumont

April 10 - June 26 2013

Delft 5

Nanochemistry for Physicists

H. van der Zant S.J. van der Molen L. Manna

24-27 Feb 2014* Delft / Leiden 5

Electronics for Physicists

V. Zwiller, R. Schouten

20, 25, 27 November, 2, 4, 11 December

Delft 5

Frontiers of Condensed Matter

Summer School 1-14 September 2013

Les Houches, France

5

Advanced microscopy

C. Danelon and others

Fall 2013 Leiden / Delft 5

Theoretical Biophysics

H. Schiessel Spring 2014 Leiden 5

Entrepreneurship T. Oosterkamp and others

to be announced

Journal Clubs any time Leiden / Delft 2 Independent study J. van Ruitenbeek any time - To be

negotiated MSc. courses To be discussed by

the student with his/her supervisor

The student should pass the exam in order to receive credits

3.2 Arnemuiden

The Casimir Spring School took place from 12 to 14 June in Arnemuiden, in the Province of Zeeland. On the first day around noon, two busses arrived with in total 120 PhD students and postdocs. The participants presented a poster or gave a talk about their scientific research work during the spring school. The poster prize was won by Fei Pei for his poster "Valley-spin blockade and spin resonance in carbon nanotubes". The award for best presentation was given to Akira Endo "DESHIMA: On-chip Filterbank Spectrometer for Submillimeter Wave Cosmology". The invited speakers Karl Berggren (MIT), Dieter Braun (LMU), Niek Lopes Cardozo (TUE) and Jean-Noël Fuchs (Univeristy Paris-Sud) presented their work and joined the spring school. Diederik Jekel gave an interactive workshop on "Science and Media". Of course there was also was some time left to get to know new people from other research groups. The program was organized by the Casimir PhD Platform exclusively for PhD's and postdocs.

This is how Vincent Mourik, one of our PhD students, experienced the school:

"The biannual Casimir Spring School was held this year in Arnemuiden. After a transfer of about 120 young scientists (PhD's and postdocs exclusively) by bus from Delft and Leiden, the scientific program started with a talk by Dieter Braun about

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the relation between biomolecules and thermal gradients. After a welcome by Jan van Ruitenbeek the first session with various speakers from Leiden and Delft followed. During the after dinner session, Diederik Jekel gave an enthusiastic and entertaining workshop on science and media. So many talks in one day makes you feel thirsty: it was party time! The next day started with a theory talk by Jean-Noel Fuchs on the properties of graphene, followed by a session of talks from the participants. Luckily the sun started shining and there was a nice breeze, so we enjoyed sailing on 'het Veerse meer'. The last talk of the day was by Karl Berggren on single photon detectors. After a disastrous soccer match we were in desperate need for another good party. Thursday morning started with the third and last session of talks from Delft/Leiden people and the final talk was by Niek Lopes Cardozo on nuclear fusion. Then it was time to reflect: the prize for best talk was earned by Akira Endo (Physics of nanoelectronics group, TU Delft) and Fei Pei (Quantum Transport Group) got the prize for the best poster. In general, this spring school was a great opportunity to share your research with people with various backgrounds from within our universities and of course to have lots of fun together during the various social activities. We're looking forward to the next one!"

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4. Research News

4.1. Timeline of research highlights 2012

JAN

Anton Akhmerov won both the Leiden ‘Discoverer of the year 2011’ prize

and the jury prize for the best PhD-thesis. Prof. Lieven Vandersypen and Prof. Yuli Nazarov are the new research

group leaders of respectively Quantum Transport and Theoretical Physics in Delft.

Marie Curie Intra-European Fellowship for Andres Castellanos-Gomez (QN/MED).

Rubicon grant for Aartjan te Velthuis (Nynke Dekker Lab/LUMC).

FEB

Martin van Hecke received NWO-VICI grant for his research on extreme phenomena in soft materials.

MA

R

Nanoscientists Kouwenhoven, Mourik, Zuo, Frolov, Plissard, Bakkers discovered the long-sought Majorana particle (Science 25 May 2012, Vol. 336, pp. 1003-1007).

Akira Endo and Paul van der Werf awarded in the 'NWO Middelgroot' programme for the development of a chip that can be used to observe young galaxies in their project “DESHIMA: nanotechnology for experimental cosmology.”

Ronald Hanson received the 2012 Nicholas Kurti European Science Prize. Gerard Nienhuis honoured by American Physical Society as “Outstanding

Referees” of 2012.

AP

R Cees Dekker received the International Society of Nanoscale Science,

Computation and Engineering (ISNSCE) Nanoscience Prize 2012.

MA

Y

Iwijn de Vlaminck, Marijn van Loenhout, Ludovit Zweifel, Johan den Blanken, Koen Hooning, Susanne Hage, Jacob Kerssemakers, and Cees Dekker discovered a key element in the mechanism of DNA repair:

Jan Zaanen elected as a member of the Royal Academy of the Sciences. Peter Kes decorated ‘Ridder in de Orde van de Nederlandse Leeuw’.

JUN

Teun Klapwijk received the 2012 Heike Kamerlingh Onnes prize.

JUL Vincenzo Vitelli received a VIDI grant for his research on "Shocks and

failure in fragile matter".

AU

G

Lieven Vandersypen appointed member of the Royal Holland Society of Sciences and Humanities (KHMW).

ERC Starting Grants for Nynke Dekker, Francesco Pedaci, Chirlmin Joo, Ronald Hanson, and Val Zwiller.

Lieven Vandersypen received STW Phase 1 Valorisation Grant for ‘IVVI-rack Advanced Measurement Instrumentation for Nano-Electronics’.

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SEP

Veni grant for Pierre Barthelemy (QN), Vidi grants for Sander Otte (QN) and Christophe Danelon (BN).

Anton Akhmerov received the Leiden University Fund Gratama Science Prize.

OC

T

Leo Kouwenhoven new head of department Quantum Nanoscience. MSc-students Christopher Watson (Delft) and Jelmer Wagenaar (Leiden)

received the Hendrik Casimir prize 2012. Anton Akhmerov won the FOM Physics Thesis Prize 2012. Gijs de Lange, Diego Riste and Ronald Hanson received the Kavli Delft

Publication prize.

NO

V

NWO Gravity Investment of 51 million euro (incl. matching by both universities) for nanoscience in Delft and Leiden: ‘NanoFront’ researchers will explore the frontiers of nanoscience in the coming ten years

Herre van der Zant received an ERC Advanced Grant from the European Research Council for his research 'Controlling Molecular Spin at the Molecular Scale.

FOM valorisation prize awarded to Joost Frenken. Robert-Jan Slager wins the Shell Graduation Prize for Physics. Yaroslav Blanter appointed Antoni van Leeuwenhoek Professor.

DEC

Leo Kouwenhoven, Lieven Vandersypen and Carlo Beenakker received a ERC Synergy Grant for building block quantum computer.

Van der Zant, Van Ruitenbeek, Van der Molen, Grozema, and Thijssen start a new research programme on quantum interference effects at the level of single molecules, funded by the Foundation for Fundamental Research on Matter (FOM).

Ronald Hanson appointed Antoni van Leeuwenhoek Professor. Casimir PhD positions won by Julia Cramer and Chris Smiet. Bas Hensen won Shell Young Talent Graduation Prize for his exceptional

graduation thesis on quantum bits in diamond. Leo Kouwenhoven received Association Medal of the Dutch ‘Genootschap

ter bevordering van Natuur-, Genees- en Heelkunde.’ Hannes Bernien (QN/QT) won University fund Delft Best PhD Candidate

Award 2012.

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4.2. Casimir theses 2012 The PhD theses published in 2012 by Casimir PhD students are listed below. Casimir offers the possibility to act as publisher and provide thesis authors with an ISBN number without charge. The theses that made use of this special arrangement have an additional mentioning of the “Casimir PhD Series” in the list.

Magis, G.: Shedding light on surface-assembled photosynthetic systems Promotor: prof. dr. T.J. Aartsma May 1, 2012 Casimir PhD series 2012-1 Morales, M.: Resistive switching in mixed conductors Promotor: prof. dr. J.M. van Ruitenbeek January 12, 2012 Casimir PhD series 2012-2 De Adelhart Toorop, R.: A flavour of family symmetries in a family of flavour models Promotor: prof. J.W. van Holten February 21, 2012 Casimir PhD series 2012-3 Mathies, J.: High-frequency EPR on high-spin transition-metal sites Promotor: prof. dr. E. Groenen March 1, 2012 Casimir PhD series 2012-4 Pezzarossa, A.: Imaging of plasma membrane domains in signal Promotor: prof. dr. T. Schmidt March 13, 2012 Casimir PhD series 2012-5 Kelly, S.: Complex oxides studied by scanning tunneling microscopy/spectroscopy Promotor: prof. dr. J. Aarts March 3, 2012 Casimir PhD series 2012-6 Nguyen, H.: Two dimensional photonic crystal devices Promoter: prof. dr. E.H. Brück April 27, 2012 Casimir PhD series 2012-7 Zyazin, A.: Electron transport through single magnetic molecules Promotor: prof. dr. ir. H.S.J. van der Zant March 28, 2012 Casimir PhD series 2012-8 Rijn, R. van: A structural view of pd model catalysts - high-pressure surface X-ray diffraction Promotor: prof. dr. J. Frenken May 8, 2012 Casimir PhD series 2012-9

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Ruijgrok, P.V.: Optical manipulation and study of single gold nanoparticles in solution Promotor: prof. dr. M. Orrit May 10, 2012 Casimir PhD series 2012-10 Beenakker, J.W.M.: Unravelling the collagen network of the arterial wall Promotores: prof. dr. ir. T.H. Oosterkamp, prof. dr. J. Frenken June 5, 2012 Casimir PhD series 2012-11 Sar, T. van der: Quantum control of single spins and single photons in diamond Promotores: prof. dr. ir. R. Hanson, prof. dr. ir. L.P. Kouwenhoven March 27, 2012 Casimir PhD series 2012-12 Etaki, S.: Superconducting Quantum Interference based Electromechanical Systems Promotor: prof. dr. ir. H.S.J. van der Zant April 27, 2012 Casimir PhD series 2012-13 Usenko, O.: Development and testing of the gravitational wave antenna MiniGRAIL in its full featured configuration Promotor: prof. dr. ir. T.H. Oosterkamp May 23, 2012 Casimir PhD series 2012-14 Gudat, J.: Cavity Quantum Electrodynamics with Quantum Dots in Microcavities Promotor: prof. dr. D. Bouwmeester June 19, 2012 Casimir PhD series 2012-15 Sousa, K.: Consistent Supersymmetric Decoupling in Cosmology Promotor: prof. dr. A. Achúcarro June 20, 2012 Casimir PhD series 2012-16 Emanuel, M.: The effect of thermal fluctuations on elastic instabilities of biopolymers Promotor: prof. dr. H. Schiessel July 4, 2012 Casimir PhD series 2012-17 Lange, G. de: Quantum control and Coherence of Interacting Spins in Diamond Promotor: prof. dr. ir. R. Hanson, prof. dr. ir. L.P. Kouwenhoven September 10, 2012 Casimir PhD series 2012-18 Keijzers, H.: Josephon effects in carbon nanotube mechanical resonators and graphene Promotor: prof. dr. ir. L.P. Kouwenhoven October 15, 2012 Casimir PhD series 2012-19

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Ren, Y.: Super-terahertz heterodyne spectrometer using a quantum cascade laser Promotores: prof. dr. ir. Klapwijk, dr. J.R. Gao December 12, 2012 Casimir PhD series 2012-20 Mol, J.A.: Single Atom Electronics Promotor: prof. dr. ir. H.S.J. van der Zant September 14, 2012 Casimir PhD series 2012-21 Verzijl, C.J.O.: On Conductance and Interface Effects in Molecular Devices Promotores: prof. dr. ir. G.E.W. Bauer, dr. J.M. Thijssen November 27, 2012 Casimir PhD series 2012-22 Mirjani, F.: Modeling Molecular Junctions - Weak and Strong Coupling Regimes Promotor: dr. J.M. Thijssen December 17, 2012 Casimir PhD series 2012-23 Huang, Z.: Nano- and Micro-Fabrication for Single-Molecule Biological Studies Promotores: prof. dr. N.H. Dekker, dr. L. DiCarlo October 16, 2012 Casimir PhD series 2012-24 Hriscu, A.: Theoretical Proposals of Quantum Phase-Slip Devices Promotor: prof. dr. Y.V. Nazarov October 26, 2012 Casimir PhD series 2012-25 Westra, H.J.R.: Nonlinear beam mechanics Promotores: dr. E.W.J.M. van der Drift, prof. dr. ir. H.S.J. van der Zant November 8, 2012 Casimir PhD series 2012-26 Labadze, G.: Electromechanics of suspended nanowires Promotores: dr. Y.M. Blanter, prof. dr. ir. G.E.W. Bauer October 15, 2012 Casimir PhD series 2012-27 Loenhout, M.T.J. van: Single-Molecule studies of the Twisted, Knotted, and Broken Genome Promotores: prof. dr. C. Dekker November 11, 2012 Casimir PhD series 2012-28 Dahlhaus, J.P.: Random-matrix theory and stroboscopic models of topological insulators and superconductors Promotores: prof. dr. C. Beenakker November 21, 2012 Casimir PhD series 2012-29

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Guedon, C.: Molecular Charge Transport Relating Orbital Structures to the Conductance Properties Promotores: dr. ir. S.J. van der Molen, prof. dr. J.M. van Ruitenbeek November 6, 2012 Casimir PhD series 2012-30 Dong, G.: Formation of graphene and hexagonal boron nitride on Rh(111) studied by in-situ scanning tunneling microscopy Promotor: prof. dr. J. Frenken November 7, 2012 Casimir PhD series 2012-31 Heeres, R.: Quantum Plasmonics Promotores: dr. V. Zwiller, prof. dr. ir. L.P. Kouwenhoven November 27, 2012 Casimir PhD series 2012-32 Astraätmadja, T.: Starlight Beneath the Waves: In Search of TeV Photon Emission from Gamma-Ray Bursts with the Antares Neutrino Telescope Promotores: prof. dr. M. de Jong March 6, 2013 Casimir PhD series 2012-33 Elmalk, A.: Exposing bimolecular properties, one molecule at a time Promotores: prof. dr. T.J. Aartsma December 13, 2012 Casimir PhD series 2012-34 Aalst, T.A.F. van der: Conformal Invariance and Microscopic Sensitivity in Cosmic Inflation Promotores: dr. K.E. Schalm, prof. dr. A. Achúcarro December 19, 2012 Casimir PhD series 2012-35 Kumar, K.: A study of electron scattering through noise spectroscopy Promotor: prof. dr. J.M. van Ruitenbeek December 5, 2012 Casimir PhD series 2012-36 Yanson, Y.: How Additives Affect Cu Electrodepositing: An Electrochemical STM Study Promotores: dr. M.J. Rost, prof. dr. J. Frenken December 4, 2012 Casimir PhD series 2012-37 Yang, J.: Hydrogen storage in metal-organic frameworks Promotores: prof. dr. T.J. Dingemans, prof. dr. F.M. Mulder October 16, 2012 Casimir PhD series 2012-38

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Rudneva, M.: In-situ electrical measurements in Transmission Electron Microscopy Promotores: prof. dr. H.W. Zandbergen January 16, 2013 Casimir PhD series 2012-39

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5. Outlook to 2013

At the time of this writing the Nanofront program has already seen its kick off with a festive and colorful event at “Lijm en Cultuur” in Delft, on 5 April. Also the theory program Matter at all Scales has been launched and many activities are taken up. Foremost, the search and hiring of talent for the first of nine new science faculty, mostly at assistant professor level, has been started. The large investment in nanoscience that NanoFront brings also poses a challenge for maintaining the balance within Casimir, and for safeguarding enough

room for the exploration of other directions in physics. This will require our constant attention, but I believe that the basis for Casimir is vigorous and strong enough to maintain interaction across all fields. On the other hand, we are also seeing the first signs that NanoFront leads to stronger ties between the research groups. In a first call for NanoFront PhD projects the majority of proposals submitted and awarded are collaborations between research groups in different subfields and between groups located in Leiden and Delft.

The initial success of the new PhD and MSc recruitment will be further implemented and refined in order to attract the best talent internationally. In parallel, we are seeing a remarkable growth of student influx into the physics BSc programs. This is all good news, since there is still a high demand for well-trained physics graduates in the Netherlands, and there are no signs of any saturation of this demand at this moment. Leiden, July 2013 Prof. dr. Jan M. van Ruitenbeek, Scientific Director