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Posted in February 2015

Third lecture Quantum Transport

was half-inteference, half-restoration of Ohm’s law – I still keep half-lecture shift. The advantage of this was that I could repeat the double junction that plays a key role in both topics. It occurred to me that the audience was more active than in former years at the interference part – good, but less active for Ohm’s law. Was I too monotonic for the second half of the lecture or the student’s tastes fluctuate from year to year?

Exact correspondence

Me and Mohammad Ansari have submitted a paper that concludes a nice piece of research on Renyi entropies. We have found an exact relation, like fluctuation-dissipation theorem, that relates physical and unphysical quantities: you can guess the implications:))))

Here is the link

Exact correspondence between Renyi entropy flows and physical flows
Mohammad H. Ansari, Yuli V. Nazarov

We present a universal relation between the flow of a Renyi entropy and the full counting statistics of energy transfers. We prove the exact relation for a flow to a system in thermal equilibrium that is weakly coupled to an arbitrary time-dependent and non-equilibrium system. The exact correspondence, given by this relation, provides a simple protocol to quantify the flows of Shannon and Renyi entropies from the measurements of energy transfer statistics.

Problem-solving session AQM

Neither Michael nor Albert could help me on this day: I had to do PSS myself. Fortunately all students were in place with the presentations and spoke sense. I also gave some practical advices on second-quantization calculations: hope it works. Besides, I asked students to fill in a survey about the course. I will investigate the data collected and present the results on next week.

Isaiah 2:4

read this on Wednesday in attempts of improving my spiritual life :)

And he shall judge among the nations, and shall rebuke many people: and they shall beat their swords into plowshares, and their spears into pruning hooks: nation shall not lift up sword against nation, neither shall they learn war any more.

Well, this hardly worked. Instead of enlightening, I felt irritation and anger. Say, 20 years ago this citation seemed to be not far from the realization. Nowadays Evil rises head again: it does so in most stupid, shameless and hypocritical fashion. Who is sillier: people raging for arms or me with my optimistic beliefs?

Third lecture Advanced Quantum Mechanics

was the core of the course: second quantization. It was pretty formal, though I did my best to outline the logics and motivation behind the formulas. The students were warned that it will be boring, so they remain rather accepting. I went slower trying to establish better contact. This resulted in a time problem: in fact, I said only few most important things about fermion quantization. Luckily, it is almost the same as for bosons.

Second lecture Quantum Transport

was on Friday. I was supposed to start with the interference. However, there was a sweet topic of counting statistics left from the first lecture. Since I liked the topic, and since one needs to brush some probability analysis to understand the issue, it went slower than expected. So I’ve managed to do only a half of the interference lecture. Well, this is rather inconvenient – to have a half-lecture shift, but I do not want at the moment to make the shift integer :)

Charles Markus

from Copenhagen, a brilliant experimentalist who has now mostly concentrated on Majoranization of semiconducting nanowires by connecting those to superconductors – has given a talk on Thursday.

He started with reporting successes in nanowire growth: nanowires can be better contacted with superconductors, and can be made in t and h shapes. He has shown “hard gap” – looked good, finally in place after years of technological search.

Then we got the report on experimental results – some fresh, right from the oven. The results in “Delft geometry” seemed clean but I did not quite see the gap as hard as promised. The results in “Copenhagen geometry” were a superconducting island has been attached to the nanowire seemed more fun – I will have to revise those carefully.

Wilfred van der Wiel

from Twente University gave a Nanoscience seminar on Wednesday. I vividly remember him as an outstanding PhD student, have not seen him for years and was delighted to see no significant change: in the position of full professor, he reminds sharp, handsome, nice and does outstanding research.

There were two topics. First one: Wilfred has investigated the conductance (well, if you can call inverse GigaOhm a conductance) of molecular wires thread in zeolyte crystal. The conductance could be changed by order of magnitude by tiny magnetic field in millitesla range. The mechanism of the effect must be related to nuclear spins and as such is the same as for the spin-blockade lifting in double quantum dots. The details remain unclear for me: yet the effect is there and is a record-strong.

The second topic has fascinated me even more. The physics was rather simple: Coulomb blockade in a pile of gold nanoparticles carelessly collected between a multitude of electrodes. A neat physical realization of complete and hopelessly incomprehensible mess. Yet it appears that that it is the mess that motivated the researcher. Wilfred managed to demonstrate that with the proper tuning (based on genetic algorithm) the pile can work as any of the logical gates! I reckon this work will have a big philosophical impact (seriously). It proves that electronic components can be made from anything (substitute “anything” with a stronger word if you like).

Facultymeeting

English at our University is very flexible reflecting a variety of meanings with very simple constructions. If you say: faculty meeting – this would be most likely the gathering of faculty of a small department, such as mine. If you say: facultymeeting – you imply an act of interaction of our Rector Magnificus Karel Luyben with a handful of people representing all faculties, levels and occupations at our huge technical university.

I have attended one on Tuesday. The previous session I was present for was three years ago. I must say I did not like that one: the people talk stiffly and officially, hardly interacted and listened to each other. This session was much better: the organization has drastically improved, the atmosphere was open and friendly, people spoke themselves out and this was helpful in many respects. Perhaps last part where we were forced to play a manager-course-like game was less inspiring for me, but the total was much better than I expected.

Among other topics, we have discussed a new political development: it looks like soon the Associated Profs will be able to promote their PhD students (it is a peculiarity of Dutch law that they cannot do it officially, and this is usually experienced as a psychological tension by many generations of Associated and Assistance profs). Great news! – yet my concern was that this may invoke more control than it is needed in intimate relation between a student and its supervisor. It appears, however, that the rector has other concerns, of more organizational nature.

We have discussed how to improve the quality of teaching: please do not smile, the discussion was rather substantive. I was surprised that many colleagues support the idea of promoting people to full profs mostly for their educational merits – at the moment, the research is main criterion. I’ve double opinion on this. From one hand, I see some people who have concentrated on education, work hard and excellent – and remain underpaid and un-promoted. From the other hand, long time ago in Russia and more recently in France I saw education-concentrated profs – frankly, I’d rather not. There must be a flexible solution to the problem.

Mutli-terminal Josephson junctions as topological materials

This is the title of the manuscript I have submitted on Tuesday with my Grenoble friends Julia Meyer, Roman Riwar and Manuel Houzet. Mmm, perhaps I exaggerate in excitation, but this looks the most significant piece of research I accomplished for last years. The preprint is not available yet, but I expect this to happen soon :)

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