Posts in category Research

I’m looking for a PhD student to work on Majorana states in superconductors.

More info:
Title
PhD position in theory of superconductivity
Research
Theoretical study of properties of Majorana states in superconducting nanostructures in the presence of Coulomb interaction and its time-dependent dynamics. Close collaboration with experimental group of prof. L.P. Kouvenhoven. Full project description can be found here .
Job description
4 years phd position
Location
Kavli institute of Nanoscience, department of quantum nanoscience

Requirements
The applicant should bear MSc title in theoretical physics or its equivalent. Experience in condensed matter physics, superconductivity and quantum information theory is appreciated.
Conditions of Employment
When fulfilling a PhD position at the FOM foundation, you will get the status of junior scientist.
You will have an employee status and can participate in all the employee benefits FOM offers. You will get a contract for 4 years. Your salary will be up to a maximum of 2,636 euro gross per month.The salary is supplemented with a holiday allowance of 8% and an end-of-year bonus of 8.33%.
You are supposed to have a thesis finished at the end of your four year term with FOM.
A training programme is part of the agreement. You and your supervisor will make up a plan for the additional education and supervising that you specifically need. This plan also defines which teaching activities you will be responsible (up to a maximum of 10% of your time). The conditions of employment of the FOM-foundation are laid down in the Collective Labour Agreement for Research Centres (Cao-Onderzoekinstellingen), more exclusive information is available at this website under Personeelsinformatie (in Dutch) or under Personnel (in English).
General information about working at FOM can be found in the English part of this website under Personnel. The ‘FOM job interview code’ applies to this position.

Contact
Yuli V. Nazarov
y.v.nazarov@tudelft.nl

Please send your CV and recommendation letters

E-mail
y.v.nazarov@tudelft.nl

Cirprian Padurariu has defended his Ph.D. thesis with me on 18-2-2013.

We did four papers together. Leo Kouwenhoven, Yaroslav Blanter, Daniel Esteve, Leonid Gorelik, Jan Aarts ans Jan Zaanen were the commitee members. Ciprian will go to Grenoble for a post-doc position soon. Good luck, Ciprian!

meeting of a new European collaboration has taken place in Helsinki on 5-2-2013. Our project is called INFERNOS, and we want to make and investigate daemons – fortunately, little ones, preferrably, at nanoscale. More about the project.

who visited me in Delft in course of our collaboration on spin-orbit effects in Josephson junctions, has got his Ph.D. degree on 31-12-2013. Congratulations! Today I have learned that he has also secured a post-doc job in RIKEN institute in Japan. This gives a chance to our futher collaboration.

has sucsessfully defended his Ph.D. thesis in Saclay, a suburb of Paris on 1-2-2013. I was in the committee. A part of the thesis was the pioneering observation of doublet state of superconducting quasiparticles, http://lanl.arxiv.org/abs/1105.5039, 40 years after its theoretical prediction. Yet it has many parts, some even more fascinating… The discussion with the opponent could have been more smooth, yet Landry managed to stay within the restrictions of formal politness.

Remarkable thesis work. And it was first time in my life I tasted home-made foie gras.

As a late gift on occasion of Orthodox Christmas, the work of me and Alina Nriscu
(read here about) has been accepted for Physical Review Letters and will be published soon.

In the context of our national grant competition I have applied with Leo Kouwenhoven for a project meant to facilitate the further exploration of recently discovered Majorana particles.

The workshop on quantum noise and measurement we are organizing in Dresden is up and running. Initially I wanted to make a collective blog for all participants but after thinking a while I decided to blog my personal impressions: emphasis is on personal, the account on the talks presented is by no means accurate and was not checked with the speakers as it should be for publication in more representative media. I’ll present my reports with a delay of couple of days.

The workshop is held at Max Planck Institute for Physics of Complex Systems (mpi-pks). Frank Jülicher, managing director of the institute, has welcomed us giving some general info about the place that makes science, runs 15-20 workshops per year and collaborates with other two MP institutes in the city, those are in chemistry and biology.

Wolfgang Belzig, our main organizer, has started the workshop providing necessary technical info.

Markus Buttiker discussed the distribution of waiting times between the events of electron transfers and its unobvious relation to full counting statistics. He discussed it first for simple electron counters and single particle emmiters where it can be easily accessed experimentally.  He presented theoretical resuts  for distribution of waiting times for the generic case of  quantum  point contact and denonstrated the crossover from wigner-dyson distribution for high transparencies to poissonian  one expected at low transparencies.

Leonid Levitov has actually given two talks in one. In the first part he discussed the noiseless electron sources where a special form of control pulse produces  states with “no splash” : electron is transferred without extra electron-hole pairs generated. For a quantum point contact, such pulses are Lorentian.In the second part, he talked about spin qubits and nuclear spin effect in there that determine decoherence of the practical qubits. He concentrated on a long-standing experimental puzzle of ultra-slow oscillations, much slower than heart beats, observed in the qubits but only in the  vertical dots. He has developed a minimal model to solve the puzzle. 3 crucial ingredients are: nuclear spin diffusion, nuclear polarisation inside the barrier separating the dots, energy dependence of triplet decay rates.

Robert Schoelkopf  shortly reviewed the research on transmon qubits (slightly non-linear josephson junctions) in Yale and summarized new results. Althouth the number of qubits in the device still does not follow Moore’s law as function of time, there is almost exponential progress in combatting decoherence sources:  T1, T2 have been improved with 3d cavity resonantors and filterinng techniques to 100 microsec range and are still improving. The main attraction of circuit QED setups is the simplicity, everything is described with Jaynes–Cummings Hamiltonian.  Operation in strongly dispersive regime enables QND measurement of photon states in the cativy and provides a toolbox for manipulating light. Robert has concentrated  on Kerr effect: frequency shift proportional to the square of photon number.  The device has two cavities: one for storage and  another for qubit readout. They produce coherent states and measure those doing Wigner tomography. Kerr  effect provides a spectacular evolution of the  states that is revealed by the measurements. Ideas for future have been discussed: to entangle the qubit and the photons in the cavity.

Jukka Pekola talked about experimental progress in investigating fluctuation relations in driven electron tunneling. He oulined  fluctuation theorem that has been investiated recently  in ETH with double-dot electron counter and related it to the entropy production. He outlined  Jarzynski inequality als well as the problems related to the defintion  of work.  Experiment was made with a split SE box where charge has been monitored. Jarzynski relation is fullfilled with 3 per cent accuracy, the error is perhaps due to non-equilibrium conditions (difference of phonon and electron temperature). Better accuracy can be achived for the general equality, or  integral fluctuation theorem that is known in markovain statistics and is valid for classical systems. What about quantum? There is  no consistent definition of work. Rather we will talk about calorimetry quantifying fluctuations of energy flows.  The plan is to study a simple two-level system and LZ tunneling.   The simulation shows that the calorimetry can work in this setup. The experiment is under way.

Klaus Mølmer gave a rather review-like talk entitled “Quantum state control by quantum measurements or what you see is what you get”.   He indicated he belongs to AMO (Atomic molecular optics) community and soon proved that this community is a way more jovile and friendly than condensed matters. His rather traditional introduction of  interpretation and collapse of the quantum state he has ended with a dithyrambe   to quantum dynamics noting that the dithyrambe also provide a perfect description of his wife (thinking back, I recognized that we have probably married twins).  He has attributed the discovery of second quantization to  Shakespire who has been constantly talking of  “a dagger” and switched to Glauber and Kraus and repetative measurements and heterodyne detection of quantum noise.  y the end we all got convinced that measurement provides better entanglement than any interaction: a point that actually never came to my non-AMO mind.

Jan van Ruitenbeek talked about his experiments on inelastic noise in nanowires that he attributed to a two-electron effect. His wires were rather short upon my taste: typically, a two-atom molecule hanging in a gap in a metallic break junction. They have resonant mechanical modes.  Jan has demonstrated good characterization and understanding of the processes forming I-V curves in the wires in various conductance regimes, from tunnel to transparent. Most important feature is the threshold of inelastic process at voltage matching the resonant mode frequency. The results on noise in this regime are fresh and intriguing: Jan said they do not match any theory. Since I was also involved with one theory he has mentioned I felt a bit disrupted. Yet the experiment is still rather fresh…

Steven Girvin gave a colloquium talk: a special talk that is intended for a larger MaxPlanck community and should be accessible for biologist. Basically, it was a compherensive introduction to quantum-limited amplifiers starting from the basics of Heisenberg uncertainty. Actually many things and particular details of the Steve’s interpretation looked pretty new and fascinating to me: it’s like as a gifted piano player discovers new sounds in a thousand-times-heard piece of classical musics. Steve has finished the talk with a copy of a postcard to Bohr from Gerlach that reported this famous experiment. He mentioned that the interpretation of the experiment was wrong by the time.

And we got to dinner and poster session.