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Posted in June 2011

Exam Quantum Transport: as an event

The exam took place today, again in that quasi-infinite building of Civil Engineering. For a change, it was one floor higher than the previous exam. So we steadily increase the exercise challenge

The weather is funny today, it tries to be hot and humid, but only reaches warm and suffocating. I felt the students are unhappy even before the examination: must be weather. There were rather many enlisted for the examination. However, I got several messages from people who could not prepare on time, and several just did not show up. Finally, I have ten exam papers to check.

My audience this year was different from what I used to have. They showed more interest and perhaps more motivation. However, they are decisively less nerdy. From a quick look at questionairs, I recognize that many have found the exam difficult. Well, that must be this funny weather…


Topological excitations

will become a part of the book on Advanced Quantum Mechanics I write with Jeroen Danon. I’m currently squeezing the material to a chapter devoted to superfluidity. It’s a difficult piece of writting: yet I dream it will be a good one.

The trick to implement the concept is to consider the superfluid in lower dimensions where vortices have finite energy and can be regarded as elementary excitations. I also hope to be able to say something about Feynmann’s roton variational function: a gem almost forgotten in modern education.

Exam Advanced Statistical Mechanics: results

I’ve finished checking the exam papers today. Good news is everybody has passed (the examination). Though a minority had to struggle for this. The distribution of the marks is pretty standard (otherwise). The fact the students made presentations was undoubtedly helpful.

However, I was dissapointed with the following. There were three groups of students: some obviously prtefer the lectures, some attended the problem-solving sessions only, some tried to combine both. Each of the three groups have exhibited distinct weak points in course of examination… While this is natural for the first two groups, and has a very straightforward workaround, I’m puzzled with the third group. The results of those were good but can easily be better.

Another point of dissapointment are the marks the students gave to our course (there is a questionaire to fill after the examination, a remedy for post-examination stress). It’s 7 in average, could be better giving amount of energy I gave..

Few skeletons in every genome

Today we have had another Kavli Colloquium. Actually, my day was busy and nervous, and I thought I could skip “this bio stuff” and concentrate at work at hand. I’ve changed the decision at the last moment and have not regretted: in fact, I think it was one of the best colloquia I ever attended.

Though there was hardly any physics. Stephen Quake, prof Bioingenering from Stanford and enterpreneur, has neatly and skilfully tuned the presentation to the perception and level of general physical audience, I appreciate much his effort to get us following. The talk did not sound any “biological” though it was.

It was about reading genomes of individual humans by means of single-molecule DNA sequencing. Stephen Quake is a leading palyer in the field. Three years ago he read his own genome for $ 50,000 cost. According to his projections, this cost can drop to $ 500 whithin years. The reading of someone’s genome can become as usual as a blood test. And perhaps will become compulsory as a drug test (in order to descrease costs of medical aid by early detection of potential gene-related medical problems). The positive sides of it are clear (though, as was stressed in the talk, less obvious than we’d like them to be). With a bit of imagination, one can picture negative sides of it (don’t want to do this here, leave it as an exercise for the reader).

When I was a kid, I read stories about scientists whose work reshapes the world within years. I think today I finally came reasonably close to seeing one. Stephen Quake looks very human, more human than most profs of science (me including). That’s why I sympathize with him and wish him to never regret the opportunities his research may unleash…

No Coulomb Blockade of Majorana Fermions

you, dear reader, and all modern society will have to live without spectacular achievements in this research direction.

My research proposal described in this post has been rejected in the course of our national competition, FOM Projectruimte. In comparison with the last year competition I invested more time to the writting, have brought more original and more experimentally relevant ideas, have discussed proposal with many and incorporated their feedback.

The result of these actions was evident and imminent: the proposal has been rejected faster and with worse mark. A modern referee does not have time to read the proposal, and expects to see the things expected. Any unexpected creativity is punished immediately, at the level of instinct.

Yet the creativity was certainly present in the marks I get. The referees suppose to give three marks: “scientific quality”, “risky character”, “total assesment” that supposed to summarize the two. Only the third one counts, while the first two are given for fun. In that case, the fun was all mine: 3.0 “scientific quality”, 3.2 “risky character”, 3.5 “total assesment”. Surprised, I asked the FOM functioneers for a comment. Got nothing except “such things happen”. They happen indeed!

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.

Exam Advanced Statistical Mechanics: as an event

has taken place today in one of the rooms of nearly-infinite building of Civil Engineering. Me and Alina made two levels upstairs and two hunderd meters in horizonal direction to reach the room. The latter appeared closed, the students confusingly flocking around. Being a responsible person, I marched the way back, got the key and marched forth. So I was already tired to start with. Fortunately, Alina has performed most of exam supervision.

Seven students have shown up. Most of them made presentation and got a bit easier version of the exam. Only one international student has decided to do a fuller version.

The impression is the exam was doable for most students. I still have to check the results and their responses on the questionaire.

Julia Meyer

has been visiting tuesday-wednesday this week. She’s a faculty in Grenoble now, after being in Germany and a loong time in US. I like very much her serious, thorough and ingenious approach to theoretical physics: something rarely seen in her generation/our field.

She gave a talk about various aspects of 1d interacting electrons. I especially liked the last part devoted to ordering of classical electrons in 1d confining potential. It’s a beautiful and context-rich problem that I also touched many years ago.

Pentecost 2011

Your way, O God, is holy.
What god is great like our God?
You are the God whoworks wonders;
you have made known your might among the peoples.
You with your arm redeemed your people,
the children of Jacob and Joseph.

This (Psalm 77) has been sung today. Looks I’ve been waiting for this message. Troubles, big and small, that hem me in, are just delusions: He will free me and save me. If I don’t see the way to deal with my woes, He’ll give the way and the means. If I’m dismayed, He’ll confort me.

Conference in Mallorca,

that’s where I’ve been sunday-thusday this week. Rosa Lopez and David Sanchez, faculties of University of Balearic islands, were so kind as to organize it, “Nonlinear spin and charge transport through nanoscopic systems” was the name, many thanks for this. Funniest thing is that we all actually work from 8 till 17, while the weather was nice almost all the time.

Things I liked included:

  • the direction of the conference: it beared non-linear stochastic dynamics flavour, the taste that becomes stronger and stronger in quantum transort research
  • talks, especially related to electron counting/pumping
  • food, and very much
  • swimming at a public beach in 1km from the hotel
  • a spectacular night thunderstorm in Hollywood style

Things I liked less were:

  • the conference mascot was a little red horny devil
  • the fact the island seems totally covered by the city
  • waking up at 2 a.m to catch the flight there
  • going to bed at 4 a.m. after the flight there
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