Posts in category Research

is a long title of a long article we have submitted to arXive today. Alina Hriscu has been working the whole year on the topic, even today in the morining. I am happy we manage to submit it yet this year.

In this article, in order to illustrate the emergence of Coulomb blockade from coherent quantum phase-slip processes in thin superconducting wires, we propose and theoretically investigate two elementary setups, or “devices”. I will post the reference to cond-mat soon.

I reserved a day, my last day in Japan, to visit NEC Tsukuba, were Jaw-Shen Tsai, Yasunobu Nakamura, Yuri Pashkin and Oleg Astafiev do almost unbelivable things about quantum manipulation. Their (pioneering) works with qubits are well-known, now in addition to it they do nanomechanics, non-linear quantum optics with microwaves and always eager to talk about new things, like phase-slips etc.

I was trying to promote the phase-slips in my talk but they’ve already did some preliminary experiments and were dissappointed. Perhaps Oleg will be able to combat this feeling. Anyway, there were more than many discussion topics, and I’ve spent the whole day talking

We’ve rounded the day with a nice party: thanks so much, my hosts.

It is more than a week I am back from NTT. It was a very good visit, both productive and informative. Here are some highlights.

With Yasuhiro Tokura, we have started collaboration on nuclear punping effects on transport in quantum dots. With Toshihiro Kubo, we have started collaboration on mesoscopic interference effects in two quantum dots. I hope very much we can bring these challenging and interesting projects to the end.

Makoto Yamashita has explained me his research in cold atoms, in particular, his studies of Bose shells. Tetsuya Mukai has shared his ideas of atom chip where several atoms are trapped above the surface of a superconductor with magnetic field of superconducting currents.

I listened to the talk of Fumiki Yoshihara from NEC Tsukuba: he presented a long-awaited experimental charactetization of flux noise in superconducting qubits. The noise seems to come from the surface. Hayato Nakano gave a detailed review of his work on “practical” measurement, theoretical research on details of collective quantum mechanics of a qubit and a detector.

Hiroshi Yamaguchi has open me new horizons in nanomechanics: he has original thoughts and plans that differ from those I accustom to. How about a computer solely based on non-linearities of nanomechanical resonators?

Many if not most discussions have been with Koji Muraki, the head of quantum dot group, his students and postdocs. I have learned about the gap at nu=2/5, was updated on charge qubits, charge measurement, exotic Kondo and, of course, on nuclear pumping effects. Here, I guess, Tokura and me were able to contribute to understanding of the experiment

is not with us anymore. This has happened two weeks ago, but I’ve learned about it only today. He was 82, and our last scientific communication was less than four years ago.

Michael Tinkham was not just a classic writer and pioneer of the superconductivity: for me, it was like the superconductivity itself. His ability to comphrehend the things about it, and his taste for novelty and unusual аspects of physical phenomena were almost beyond imagination. In his advanced ages, he looked nothing like a monument to his own merits: rather, he acted as a person in very beginning of his scientific carrier, looking for news and being eager to learn.

Our last communication was about quantum phase slips: he wanted to achieve an unambiguous experimental proof of their existence.

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

was a topic of our deep considerations with Jeroen Danon. These considerations have started when Jeroen was a second-year ph.d. student, and now, as Jeroen is already more than a year in Berlin, finally converged to a form of a paper submitted. You can find it here.