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Quantum Noise and Measurement in Engineered Electronic Systems

This international workshop we have organized with Wolfgang Belzig and Michel Devoret has ended succesfully, mostly because of local organizer Katrin Lantsch. We got quite some enthousiastic responses and are basically satisfied. Time allows I will blog the notes I made last week.

Anton Akhmerov

has been visiting the department today. Guess it’s been quite a preparation for him since he conquered many hearts of our faculty. His talk was prepared in a color scheme that I by the lack of experience regarded as gothic: However, the students have corrected me.

Anton combines intellegence and ambition with a great deal of flexibility and does not drink alcohol. I foresee splendid future for him.

Happy New Year

to you, dear reader! I wish you not to get bored, and not to loose your mood in all troubles the year might provide. The Lord will look after us all, just keep fit and open to him.

Old and new

All right, it’s almost time, time to think of good and bad, achievements and losses, old and new, whatever silly it is.

My Lord kept me and keen reasonably healthy and active. Kids gladden my heart. I could enjoy love and friendship. As to research, six papers have been published, two in PRL. We have made 11 arxiv submissions. I got 475 citations this year reaching h-index of 47. I’m happy I could work on Renyi entropies and hope to continue with this, we cracked the polaron in carbon nanotube. I’ve learned about several interesting experiments to think of and had a couple of prospective ideas. I made into several very good grant application teams, this schould work over a time. I collaborated with visitors, Izak Snyman and Tomohiro Yokoyama.

On negative side, my laziness and lack of feeling for my neighbour yet prevail. I could not finish papers I would have to, no grant application was sucsessful, many things planned have been smoothly transferred to next year plans. One of my best scienific achivements has not been sufficiently appreciated. The “weather” for research becomes increasingly bad: less and less money for real science. And overall “wheather” might be better, with all signs of economical and political instability appearing as ugly blotches at the made-up face of our prosperous civilization, that accompany signs of moral degradation and devotion to sin.

And my own aging, on the top of all. Less people smile at my jokes and understand my motives. Less news in my life, all runs along the trajectories known, and to my astonishment I even do not get bored with this…

Challengies for next year. I have to finish the book with Jeroen, and pretty soon. I need to learn how to run the group, and actually why. And grant applications, articles, students finishing, students (hopefully) coming… I just do not want to be boring, you know.

Fritz and Hans: an attempt at phenomenological understanding

This is a title of my contribution to the last Kavli Newsletter. I’ve written it a while ago and almost forgotten about, yet Huub Salemink was as kind as to remind me today. Here it goes:

The immediate motive to write this column is evident: J.E. Mooij was awarded the Fritz London prize. And though he has to wait for half a year to get his hands on it, we are all glad, consider it as our common achievement, and congratulate him from the depth of our common heart. Yet here I’d like to attempt a deeper study that, for the absence of exact microscopic theory, is bound to be phenomenological. By virtue of this approach, I have to disregard any personal detail however important it might seem.

The phenomenon of Fritz London is evident and lies within penetration depth. Foreign experience cannot be underestimated: it took only a year for this 1933 refugee to come up with a seminal theoretical contribution to superconductivity theory, long before this theory came into existence. It was a gem of phenomenology and implied a professorship. But how could an émigré penetrate the hearts of Duke colleagues so deeply as to make Fritz into a prize? When John Bardeen got this prize he did not hide it in his pocket; after a while, he returned back an amount 10 times greater to the prize fund, and that was no grant money. While we do not know what attracted him that strongly, it is well established that superconductivity, and thus research thereupon, requires attractive interactions.

The phenomenon of Hans Mooij is perhaps more complicated and certainly less explored. Why would a successful Shell employee run back to science? And if really looking for science, why would he run to a place where leading professors were not burdened with Ph.D. titles and published only once every two years in a local journal? And, if adjusted to such an environment, why work persistently at changing it into a Nature-publishing collective where almost any Ph.D. is a professor? Why, upon coining your own scientific reputation, would you care about, promote, and defend the research in fields so different from your own? Being successful in all that, why still look for new topics to investigate? Well, it is clear that the usual assumption of local, or contact, attractive interaction does not work here. The interaction must be global and arise from a kind of unbroken symmetry where your individual research and success is equivalent to those of others.

I wonder if we can comprehend this unusual symmetry in more exact terms. Actually, I do not care if we cannot. The point would be to accept its existence at the phenomenological level, understand the possible (and perhaps impossible) experimental consequences, and utilize the phenomenon.

The author is indebted to J. E. Mooij for numerous manifestations.

Polarons in suspended carbon nanotubes

this news deservers more comment and expressiveness for me, but I have to keep it short:
Izak Snyman and me have submitted today our study on polarons suspended. You can read it here, please enjoy!

Fifth lectrure quantum transport

is traditionally devoted to Coulomb blockade, and marks an important change in the course, that from scattering to interacting electrons. My assesment of the lecture is rather positive, I was able to tell everything I wanted. I could speak more coherently, and give less details in one place and more in another.

The interaction with Sankore 3.1 is still not ideal. I have discovered a problem with pdf font conversion yesterday in the evening and could not solve it with usual methods, so I went to bed at 1:30 am only. I ended making images of each pdf page, arranging the images to a pdf again and using Sankore 3.1 on the result. It worked, but the image resolution is rather low, it looks ugly upon zooming.

Ioan Mihai Pop

has perfomed his Ph. D. defence on Feb. 15. He made his Ph.D. research in Grenoble, with Wiebke Guichar and Bernard Pannetier, in experimental physics of Josephson arrays. There were several important achievements in the course of his term, two are related to phase-slips in the array, that is, “my” stuff. David Haviland, Alexey Ustinov and me were foreign referees present at the defence, which was excellent(I mean, the defence).

It was fun to drop to Grenoble for a day and meet old friends. I also hope to be there in September on other occasion.

Giant current fluctuations in an overheated single-electron transistor

, an article with Matti Laakso and Tero Heikkila, has been accepted to Physical Review B these days. Very productive collaboration, I hope I can do more with my Finnish colleagues.

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.


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