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Posted in August 2010

Assumption of the Mother of God

is a great feast of today. In some churches, they call it Dormition or Falling Asleep. This is to stress that the word “death” or even “passing away” does not really apply to Mary of Nazareth. And, after all, to all of us. Or, in more precise terms, it is up to us if this applies.

For a long time, it was difficult for me to accept the fact. No, I did like to believe in this. While recalling my dears that are not here any more, I always feel that they are somehow alive: even by time I was an atheist. However, it seemed impossible to perceive the life after death, and especially the retribution in hereafter, as something systematic, as a “natural law”. All stories or descriptions I have heard or anything I could imagine seemed so earthy, so bound to the reality known, as not giving me any thrust.

Upon age I’ve undrestood I came in terms with the concept. Learned that there are real things that I cannot imagine. Learned to thrust even if I cannot imagine.

Week Konstanz

This is yet another overdue report: week 16-20 August in Konstanz.

Konstanz is a beautiful city at Bodenzee lake and German-Swiss border. My old collaborator Wolfgang Belzig works there. Yet none of those was a reason to visit there this time.

Guido Burkhard and Daniel Loss have had a splendid idea to organize a school/workshop on spin-based quantum information processing. Besides an interesting and “hot” central topic, the gathering was exceptionally well planned: all aspects and directions of the activity were represented by prominent speakers giving long and informative talks, younger people presenting newer things in shorther talks, big number of students with posters, opportunities for discussions etc. Not mentioning exclusive location and good food:)

I talked about spin superconducting qubits.

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.

Grand Idiotic Hike

I’ve made in Aspen this weekend. My initial plan was to make a circuit tour in Hunter Creek-Frying Pan wilderness area east of the city to cover 40-50 km of trails. I was planning to start Friday morning and, with some luck, be back in town Friday close to midnight, or, without, Saturday morning. Eventually, I was met by mountain resque in 3 km from the town: that was Monday 2:30 pm. A long relaxing weekend.

My mistake had deep roots: relaying on indirect sources of information like Internet and topo-maps. The trails looked perfect on the maps. Four years ago during my previous visit to  Aspen I made 40% of the circuit to find resonably well-marked and walkable trails. By symmetry consideration, that should apply to the rest of the circuit. It took me a while to understand that the trails became increasingly worse and eventually ceased to exist. By that time it did not look like a good idea to turn back, since there were no trail in any direction. Indeed, later I have heard that the trails are abandoned decades ago. 

My GPS unit honestly wanted to help for 2,5 days, last half of the day showing 0% of charge remaining (and the trails that unfortunately did not exist). Later I had to relay on my recollection of the local geography and teenager experience of beyond-the-route hiking in Siberian hills. The later was not completely irrelevant: I would define the local forest as mountain "taiga", and the landscape of creek-cut hills and rocks looked familiar.

Unfortunately, I think I developed a light mountain madness: sometimes I’ve heard and seen strange things and decisions I made on the way , while looking back on it, did not look at all optimal. For instance, when I found a trail it took me several attempts to figure out a good direction: the right answer eventually was that no direction is good. If there were no such things, I’d be back on Sunday morning.

Anyway: my wife called mountain rescue Monday 2 a.m. and they meet me several miles near the city. While I did not need the directions anymore, I certainly appreciated the lift to the town, luxurous meal and tons of warm attention  they provide. Thank you, Scott Messina, for finding me, Hugh Zuker for being a president of such needed NON-PROFIT VOLUNTARY organization. They of course cooperate with law enforcement: it was my pleasure to meet the sheriff and his deputy. Many thanks to everybody.

Finally, I propose that Pitkin county (that could be the richest in US) invests in restoring the trails. First, that could save several lifes of Internet-dependent geeks, Second: though this may sound shameless after making so much idiotic things, but I enjoyed the hike. It’s a truly beautiful wild country. Would not mind to repeat it: if there are trails…



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.



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