De meningen ge-uit door medewerkers en studenten van de TU Delft en de commentaren die zijn gegeven reflecteren niet perse de mening(en) van de TU Delft. De TU Delft is dan ook niet verantwoordelijk voor de inhoud van hetgeen op de TU Delft weblogs zichtbaar is. Wel vindt de TU Delft het belangrijk - en ook waarde toevoegend - dat medewerkers en studenten op deze, door de TU Delft gefaciliteerde, omgeving hun mening kunnen geven.

Posted in November 2010

Visit NEC Tsukuba

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.

Good time at NTT

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

Michael Tinkham

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.

Nuclear spin pumping and electron spin susceptibilities

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.


Tokura-sensei was so kind as to drive me and Kubo-san to Hakone on Saturday, Nov. 13. Hakone (箱根 ) is a mountainous area west of Atsugi. Hakone checkpoint used to protect the only pass connecting Kyoto and Tokyo plain areas. Hakone houses many hot spring resorts, offers astonishing views of lakes and mountains, Fuji-yama included, and is a popular destination for domestic and foreign tourists.

So we hiked over mountain trails that were enhanced with bamboo trunks but did not get any easier. We smelled sulfur of volcanic vapour. We got into unearthy valley of Owakudani where smoke, hot water and heat come from the ground. We ate famous black eggs cooked in sulfur-reach naturally-boiling water. We took a cable car to get the views of Fuji and the lake Ani. We ate observing lavish pirate ships that cruised the lake. We took a good stroll along the lake shore.

It was a wonderful day, I am thankful for that.

O-yama and Shonan

This is a report of my activities in the weekend 6-7 november. I found myself in a semi-urban- semi-rural area of far Tokyo suburbs that spread tens of kilometers in any direction. The area is pleasantly exotic and convenient (you kind of cannot get lost in mountain taiga), so eventualy I opted for long walks.

My Saturday destination was O-yama, 大山, that is, “Big mountain”. Ten years ago I sucsessfully climbed it, and that was my intention for this time as well. However, I could not find the path I took ten years ago (they say it used to be female path to this holy mountain). I took the main path starting by the cable car station, male one, one who everybody takes. It was rather crowded. The path eventually consisted an ancient-looking stone stair that interrupted and changed directions randomly, following the slopes. After some time, I have reached lower shrine, at half-way climb, where everybody has been going. There was crowded, one can enjoy magnificient views of the valley below, or temples around. After resting a bit, I got a strange thought: perhaps, I do not have to get to the top at all. Perhaps, after tramping 17 kilometers of suburbs and hopping the stone stairs it won’t be such a joyful adventure. And I followed the thought. Getting wiser?

On Sunday I headed straight south. I seldom get to Pacific ocean and did not see it for ages. So it was 15 kilometer walk to Hiratsuka, to famous Shōnan (湘南 ) beaches. Several kilometers south to Atsugi I was able to get a glimpse of Fuji mountain, first time in my life. Hiratsuka appeared to be a nice and clean resort city, somehow resembling Schevingen. The beaches were good, also of Schevingen type. The difference was the sand color: volcanic activity in the area made it black. You guessed it correctly: it was rather crowded. People have been playing volleyball, fishing, some teenagers have been actively surfing ( ocean waves). Nobody swam, though the weather was fine and water did not feel too cold. So I also suppressed this natural desire (getting yet wiser?).

NTT Basic Research Laboratories

is where I am now. They are situated in Atsugi, Japan. I have arrived on Thursday afternoon so it is my second working day. I’m forging collaboration with Yasuhiro Tokura, head of Optical Science group, and his colleagues. We have many topics where we wish to interact: nuclear effects in quantum dots, long-range mesoscopic fluctuations in quantum dots, and general transport, you would not be surprised: in quantum dots as well.

The lab is an oasis of peace and order if compared to any university. People are concentrated on science. They are polite and considered. Every door is opened with a card, so you physically cannot go where you are not supposed to. Lunches are perfect, coffie is always available.

And I was happy to discover that Hans Mooij is here as well, perhaps attracted by peace and order. Delft is everywhere.

Quantum Noise

and Measurement in Engineered Electronic Systems: it’s a great topic of an upcoming workshop in Max-Planck-Institut fur Physik Komplexer Systeme, Dresden. Finally good news: the institute has recently confirmed the acceptance of our application. The organizers are Wolfgang Belzig, Michel Devoret and me.

The workshop will be held in October 2012, so we have ample time to organize everything.

© 2011 TU Delft