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Posted in October 2011

Quantum to Classical Crossover in Mechanical Systems

This was a workshop held in Lorentz Center this week. In short, nanomechanics. It has been organized by Dirk Bouwmeester, Yaroslav Blanter, Herre van der Zant, and Eva Weig. A peculiarity of the organization were very long talks: 1.5 h with discussion. That’s not always bad, yet in this case a speaker usually attempts to say everything he/she knows.

I was able to attend on Monday, hope the most interesting day of the workshop. Andrew Clealand gave a extensive talk about cooling a resonator with a quibit: in his case, with superconducting qubit. He started with a electromagnetic resonator where very unusual and beautiful states can be formed. Further he described a mechanical resonanor with gigantic piezoelectic transduction. There, the results were less spectatular, though the manupulation of states has been clearly demonstrated. Pierre Meystre gave a detailed overview of the ways to couple and manipulate two resonantors, with emphasis on optomechanical systems. Jörg Kotthaus has presented an account of his research on qualifity factors and transduction of microoscillators. Our Gary Steele talked about nanotubes: and yes, he reviewed almost everything he’s done, yet it was interesting to hear.

I met some people I have not seen for a while, Phil Stamp including.

David DiVincenzo

has recently moved from IBM to newly established Institute for Quantum Information in Aachen/Julich. So it was reasonably convenient to him to drop by Delft and give a talk. Leo DiCarlo has presented the speaker as “a man of selective criteria” hinting on DiVincenzo criteria. David talked about error correction codes in quantum algorithms. His main message was that from a multitude of possible error correction circuits one should concentrate on those who have a geometric meaning and can be thought of being performed on elements of a two-dimensional periodic array. He stated that such schemes are now close to practice and appealed to Leo DiCarlo to move to this direction.

I liked the talk that for me had a series of surreal elements as if I’ve been dreaming (swear I have not). Let me list them.

  • I seemed to understand the subject: all my previous attempts to understand the principles of quantum error correction resulted in much deeper sleep
  • By the end of the talk I had a question. When I started to speak I recognize that I have already posed this question to David in the course of his talk in Delft in 1999.
  • This time David gave a very convincing response
  • David referred to works of Alexey Kitaev and showed his photograph. I immediately recalled that both David and Alexey were active in the field of quasi-crystals (Nobel prize of that particular day, see previous post).
  • So I started to think of implementation of error correcion codes in quasi-crystal lattices. Since I understand no heck in both fields I was trying to combine, that was not an extremely productive thinking. But just in case: let me claim this spectacular idea!

On crystals with five-fold axis

Five-fold symmetry axis is not compatible with translational symmetry and therefore with crystal order, that’s it. To be read in textbooks, and all clever boys and girls do know this. This year Nobel prize in Chemistry celebrates an experimental disproval of this mathematical statement, a remarkable discovery of quasi-crystals, the discovery made accidentally, met first with disbelief and them with euphoria, and almost forgotten now.

Quite some time ago Leonid Levitov showed me a fresh-pressed journal with a diffraction pattern photograph that clearly manifested this five-fold axis. Being a reasonably clever boy, I reacted with expected furiously, citing the textbook. In a couple of weeks, I listened to the talk where Kalugin, Kitaev and Levitov presented the first theory of quasi-crystal order, a break-neck idea of hidden higher-dimensionality of the material. (Actually, I still remember some details of the talk but can’t recall who of the three gave it.) All the authors were PhD students(Correction: was reminded on 9-10-2011 that they were master students)), all were below twenty-five. It looked like golden times of physics came back.

Well, after a while other ideas took over. The authors kept working in the field for a while and contribute a lot.

I find it exteremly unjust that their contributions have not been even mentioned in the scientific blurb that explained the prize. Well, these chemists remain chemists…

On distant supernovae

2011 Nobel prize in physics has been announced. While it did not go to me nor to my friends/colleagues, I think I am reasonably satisfied with the decision. The Nobel committee has acknowledged that we live in Universe, moreover, in an expanding Universe, moreover, the expansion goes faster and faster hinting on lots of dark matter. The cosmologists may be boring and arrogant, and may exploit the natural interest of a taxpayer to things “above” without any measure. Still, they are busy with right stuff.

There’s a really well-written blurb about scientific background
at the Nobel site.

© 2011 TU Delft