Posts in category Research
Vincent Mourik
has graduated today with 8,5 mark. I knew Vincent a bit and I must say I underestimated him, perhaps because he’s rather timid. There was not only a spectacular result in his thesis: it’s been very well written, and the presentation was close to ideal. Vincent collaborated with Ciprian and will remain in Quantum Transport group as PhD student. Best sucsess, Vincent!
Third week Aspen
This is another overdue report about Aspen: last week of my attendance. By the time, topological workshop was more or less gone. On Tuesday ( I missed Monday because of the idiotic hike) I listened to the talk of Amir Jacoby who presented the experimental results about Quantum Hall edges revealed by looking at coupled cleaved edge wires. The system allows to check the tunnel conductance between the wires as function of voltage (energy) and magnetic field between the wires (momentum) and one can read the dispersion curves of edge excitations out of this. Wonderful experiment has shown many featurutes predicted by simple and not-so-simple theories. Amir also told about equlibration of the edge channels in fractional QH regime: I have to read more about this, some data looked quite puzzling.
At the same day there was a collection of 5-minute talks by workshop participants, very informative. I was quite surprised by an idea presented by Netanel Lindner(?): the topological ordering in topological insulators can be punctured as a inflatable ball by applying an a.c. field resonant to the energy band at a line in k- space. I did not believe this at once, and Daniel Arovas was so kind to explain this to me in more detail after the session. There are obvious difficulties with the dissipation and a quantity to observe but this looks like a rich idea.
On Wednesday, Anton Andreev explained his work with Spivak and Kivelson. That is a previously unexplored case of hydrodynamics: somehow, if I got it correctily, thermal conductance of a charged liquid can define its electric conductance. This leads to a rather paradoxical situation I have discussed with Andrei afterwards. I am not sure yet that I understood how this works.
On Thursday, there was a colloquium by Paul Goldbart, a rather complete account of his work on mesososcopic superconductivity, with many references to experiments of Bezryadin. Afterwards I got plastered as I did not do for quite long. Do not think that anything in superconductivity gave me a reason for this: rather, I guess I experienced sadness that Aspen weeks have passed that quick and without immediate results.
With Leonid Glazman, we finally turned to kinetics of SNS and first usage of adiabatic basis. There were rather unexpected difficulties with this, and we become optimistic only on Friday (perhaps because we had to). I still have to summarize these developments in the form of notes.
Second week Aspen
This is an overdue report about the activities in Aspen. As to the talks I attended and liked they were as follows:
Fiona Burnell from Oxford told us about universal phase transitions in topological lattice models. While I guess I understood the main idea and appeal of the topics, there was a clear inverse perspective effect: the more details and more explanations Fiona gave the lesser my understanding got. Partly this was due to the specifics of the workshop talk: you want not only be comphrehensive in general, you wish to demonstrate that you belong to a specific community… Short way to do so is to use a specific slang without explanation,
Felix von Oppen told us about energy relaxation and thermalization of hot electrons in quantum wires. There was a tedious calculation meant to illustrate electron-hole asymmetry of energy relaxation in 1d geometry and explain thereby recent experimental findings of Amir Yacoby. The theory is all fine while I am not sure about the answer upon substituting the numbers: looked too big of an effect…
Chetan Nayak from Microsoft Station Q gave a talk about recent developments with Ising anyons and nearly Ising anyons. This reported an attempt to expand possibilities of topological quantum computation beyond its known limits, beyond braiding. While I appreciate vigour, determinance and beyond-the-road inventiveness of the authors, I could not accept the stream of the research. As to me, if you formulate a problem, you’d bring an answer at some stage. Reformulating the problem again and again just because the the answer does not look interesting not satisfying topologically-ideological constrains that lay beyond the subject itself must be an interesting educational game.
Colloquium by Joerg Schmalian, Iowa State, on the physics of Fe-pnictides was pleasantly reminiscent of my solid state youth. Was all as in good old days: new physical system, simple phenomenological approach, intriguing new symmetry revealed…
Our exercises with Leonid Glazman were about density of states in SNS systems in specific limits. Each day brought a new fancy answer that provided a fascinating picture and at the same time could make an exemplary problem in mathematical analysis: at the second-third year level. If we were ph.d. students we would know how to fill our thesises: unfortunately, the happy times have passed and, by the end of the week, we’ve decided to think of more serious stuff.
First week Aspen
Aspen does not appear to be a good place for blogging: the second week is almost over, yet I still have to write about the first week.
Aspen Center for Physics is certainly a good place for doing science: it hosts many workshops during summer, and a bunch of people communicating, writting formulas, listening to talks, making fun and hiking in nearby mountains. There are two workshops going simultaneously: Low Dimensional Topological Matter (here matter as in consensed matter not as in matter of routine) and Quantum Many-Body Physics in One Dimension. According to traditional classification, most participants belong to strongly correlated community, to more theoretical and abstract part of it. While it’s not precisely my community, I certainly enjoy intellectual intensity and logical taste of their discussions, something I sometimes miss in quantum transort. I could listen to a talk not understanding a bit and still find it interesting and inspiring.
As to talks, we,ve got plenty for workshops of the style. Yuval Oreg told about Creating and braiding of 1D non Abelian Majoranas (that is, 1d superconductor with spin-orbit in polarizing magnetic field). Thierry Giamarchi discussed Non-Luttinger liquids (that is, cold atom chains). Alexey Bezryadin has reported his quest for phase-slips in 1d superconducting wires. Jay Deep Sau told about Majorana fermions and non-Abelian statistics at the interface of ordinary semiconductor and superconductors (that is, polarized superconductor again).
I could not escape entaglement over here, of course. Daniel Arovas gave a colloquium on that in complicated many-body states. I was surprised by abundance of the results he reviewed. Besides, I discussed the stuff with Israel Klych and Karyn Le Hur: they also did a work on Renyi entropies and their relation to full counting statistics.
Alina and Ciprian were kind enough to send me frequent progress reports about our projects, so I do not feel guilty for letting them alone without my valuable supervision.
My personal interest is in collaboration with Leonid Glazman, we go on with the stuff I described in Grenoble. The progress is slow, and we encounter many strange things not fitting our plans, but we do not give up. It’s like a difficult hike without a good map.
As to hikes, I wish I could enjoy them as usual. My last time in Aspen was four years ago. When I get to a familiar Ute trail, I’ve clearly understood that that time I was four years younger. I could not make it to the top of Aspen mountain… Providence was so much displeased with my hiking performance as to dispatch a truck with a good Samaritan of driver: he brought me down to the town saving me from hiking back in darkness. Another attempt was to bike to Snowmass village: again, I was dissappointed with my performance, though I could breath normally at least a third of the way. Looks like I could not adopt to height during the whole week.
Busy week before Aspen
I’d love to write more to the blog this week, but, owing to bad organization, the week has turned busy. On Sunday I’ll depart to Aspen, Colorado for three weeks to attend traditional summer workshop in the Physics Center over there. So I had to do a lot this week, and the lot appeared to be lotter than usual. I was writting response to referee reports with Alina, freshly reboot the project with Mihajlo (partly, by means of a bureacratical evaluation procedure: it may work as well), do noisy with Ciprian (and perhaps we will soon explain some experimental puzzles), spend half a day discussinng quantum bifurcation with Alec Massen van der Brink and talk to another dozen of people (actually counted…) Doing all that was fun, yet some important things I had to skip: bad feelings…
To Colorado!
No ERC Advanced Grant
So I have learned today that my ERC proposal is rejected. Therefore there will be no unified theory of quantum transport. Instead, somebody will excercise first-year physics or kick molecules over the substrate. Will write more about when get to normal.
Still a chance to devise a polaron …
In the end of April I’ve submitted a grant application to FOM (see http://yuli.weblog.tudelft.nl/2010/05/01/proposal-fom-projectruimte) whereby I hope to get a Ph.D. student to devise polarons in carbon nanotubes. Today they annouce the results of the first round. My application is still pending, however the chances for its approval do not look much better than in the beginning…
They say they got 42 applications and can grant no more than a quarter. Several proposals have been immediately approved, some have been rejected while mine belongs to the group of 12 that they want to send to the referees. Wish me some luck.
In case you wish to see the proposal, I’ve uploaded it to Rapidshare
http://rapidshare.com/files/405740053/fom_projectruimte_2010_Nazarov_v2.pdf.html
Enjoy.
Pieter de Groot
born in Marken, has reached the Ph.D. title today. His promotor, Hans Mooij, flanked by Kees Harmans, has stressed several times that in case of Pieter the title should read "doctor of engineering" thereby showing his appreciation for perfect designs of qubits and read-outs Pieter has accomplished in the course of his promotion work.
The work presented in the thesis is of exceptional quality and resonance. However here in Delft this is very usual. What was unusual is a high quality of the defence: with no exaggeration, it was one of the best defences I ever attended. Pieter managed not only to answer all the questions and keep the opponents at bay: he did so without telling any unjustified and/or scientifically ambigouos things. His propositions were both provocative and formulated in such a way that people with opposite views could sign them: Pieter could be indispensible in formation of Dutch government.
Yet I hope he would not rush to politics and stay in research: we all would profit form this.
Diego Riste
nato ad Ancona, graduated today. I was in the commission and was surprised to learn that diamond dust is not at all toxic: I always thought it was a poison of choice in Middle Ages. Diego did quantum manipulation of NV centers in diamond in the group of Ronal Hanson and has produced a good harmonic thesis where everything was present: theorical background, very sucsessful experiment, a promising analysis of possible applications and even a bit of physics.
He’s got a mark that is highest possible one in quantum transport group, 9. Good luck, Diego, with future research.
Juriaan van Tilburg
student of Leo Kouwenhoven, has got this Ph. D. title today. He’s fabricated, contacted and measured more than a thousand of nanowire samples, so their total length spans almost a centimeter. Close to the end of the Ph.D. term he’s been awarded by – how he puts it – "intense happiness" of observation of single electron spin. Good work, good thesis, good person: the whole science is founded on shoulders of such people.
Though I had to object one of his propositions. He wrote that the influence of the position of plant Venus on one’s birth is identical to that of an apple at 1 cm distance. I believe that this statement has arised from a theoretical estimation based on a model where the concrete details of birth process have been oversimplified if not at all neglected. Well, it’s just a matter of experience…