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Posted in June 2010

Sad news

I have learned today. Alex Savchenko, professor of condensed matter physics of University of Exeter, has passed away on Sunday as a result of a sudden heart failure. Strong, handsome man, always smiling friendly. Sportive: first dan in aikido. This could happen to anybody, not to him.

Alex Savchenko did quantum transpot under resonant conditions, studied interaction effects, Quantum Hall. Did many spectacular noise measurements. Last years was one of the leaders of graphene research in UK.

Me and my students have intensively collaborated with Savchenko and his team in 2002-3. There were more collaborative projects that we have postponed. Seems like indefinitely…

Grant rest, o Lord, to the soul of Thy servant Alexander.




Altai summary

I’m back from Altai, the trip took 33 hours from door to door. Time to summarize things learned and impressions collected.

1. Qubits and nanomech grow closer and closer together.  Recent works of NEC group in collaboration with Munich prove this. 

2.  Astafiev from the same NEC group bets to re-do all non-linear atomic optics with a qubit and is close to completion of this challenging plan. If accomplished, qubits as artificial atoms will acquire all the functionalities of traditional atoms. So we do not need old atoms anymore: we can safely replace them with qubits.

3. Theorists can be useful in revealing and studying problems the engineers of Intel corporation will enconter next year (talk of V. F. Lukichev, Institute of Physics and Technology, Russian Academy of Sciences)

4.  Varelii Vinokour from Argonne National Lab has made a major contribution to the art of scientific presentation. First half of his talk has been devoted to scrupulous description of wrongdoings of his scientific opponents. He also mention that these wrongdoings were instrumental for his accelerated promotion to Argonne Distinguished Fellow. Unfortunately, I appeared too conservative for this novel type of talk and so-extended introduction did not help me to gasp the scientific side of the conflict described.

5. Fluctuation-dissipation theorem is wrong: this was a claim of prof. Averin from  Stony Brook. Yet during the talk we have learned that FDT is ok: rather, there seem to be a problem with description of high-frequency thermal conductance with Kubo formalism.

Qubits in Altai mountains

do occur. It’s a second day I am here, in the heart of Altai, mysterious craddle of all turkish nations, among mistly forests, rocky hills, and unbelievably wild rivers: water seem to be boiling at all times.

There is a workshop in nanotech organized by people from Novosibirsk State Technical University. It is dominated by quantum superconducting devices and Russian-born scientists who work and live in West. The hidden agenga is perhaps the organizers wish to run a full-scale international conference, not sure about the place and use former compatriots as testers. 

This is an unnecessary precaution: the place is well-run despite being in real wildreness, welcoming and the surroundings are magnificent. The only point it is a bit difficult to reach. We flew to Novosibirsk, that is an adventure by itself. Then we made a 10-hour bus ride through Siberian steppes. Those are usually dubbed cold. I wished it were true on that day: there were thirty in shadow, and there was hardly a shadow. It begun to rain only soon after we have reached the place…


more about Dresden

Let me summarize my impressions from Dresden workshop that I’ve left on 17-6-2010. Its official name was "Quantum Information Concepts for Condensed Matter Problems". It was very timely to consolidate an emerging community of condensed matter theorists: unfortunately there was just a single experimental talk, very good one but yet not in condensed matter. 

The organizers where: 

Ian Affleck (University of British Columbia, Vancouver, Canada)
Masud Haque (MPIPKS Dresden, Germany)
Ulrich Schollwöck (LMU München, München, Germany)

A typical activity reported in the course of a workshop is to take a complicated many-boby wave function such as of Fractional Quantum Hall state, or Heisenberg chain, numerically compute entanglemet of a part of the system, and compare it with known theoretical predictions. Both making predictions and computing is challenging and difficult. The expectation is that the activity will let us understand more about the properties and internal structure of the complicated many-body states, and it looks like there is some progress here.

Another activity is connected to the words "quantum quench": perhaps the most buzzing word combination at the conference. In this case, the dynamics of entanglement is of interest. The value to predict/compute is the change of entanglement that takes place when two parts of the system are connected and disconnected. This is related to my attempts to study the transport of quantum information quantities.


Dresden workshop entanglement

is where I am now. It’s not quite my usual community, this makes talks challenging to follow and people interesting to meet. The community is not quantum-informational either: mostly participants are condensed matter theorists interested in application of quantum informational quantities to complicated many-body wavefunctions. My talk yesterday was about the current research on tunneling of Renyi entropies.  I also gave a general overview of my own research agenda in this direction. It was so entertaining to talk about these future plans that I’ve lost the feeling of time. It did not happen to me recently that I could present only a half of the talk…

Some people came over here from the recent workshop in Osterreich and brought good news about Alina and Ciprian: looks they manage to produce a good impression and made me happy thereby.


Visit Levitov

Leonid Levitov was visiting this week wednesday-thursday.

Leonid Levitov is a brilliant theorist with persistent interest to experimental problems. He is employed in MIT. I know him quite long: we have had the same supervisor, Gerasim Eliashberg, at Landau Institute in eighties of the century past.  

The visit has happened rather unexpectedly. I wrote to Leonid asking a question about his recent work, the answer was important for me. He answered he could not think of it since he’s packing a suitcase to go to Europe. Yet my mail brought him to a good idea: to include Delft into his European tournee.

That was great. We’ve got a nice and very fruitful discussion about entanglement production: it went through several stages and will perhaps result in a small collaborative project. Yet I was not only one to profit from his presence: Leonid has many contacts in Delft, like Hans Mooij and Teun Klapwijk and is always eager to make new ones. So he performed like  a chess master giving a show of simultaneous games: he quickly changed from one "opponent" to another.

Leonid also gave a seminar about a plausible scenario of exciton condensation in bilayer graphene.  

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