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Posted in 2009

Eighth lecture advanced quantum mechanics

is one of few lectures in the course where calculational flow is being combined with flow of physics: the number of variuos situations we address is significantly bigger than in most of the lectures. There are also pictures. The material is such that a good presentation seems easy. There was a little time problem before the break and in the end of the lecture, I could use several more minutes. The overal timing was however OK. More serious problem is that I am still missing rhythm of the lecture: some pieces I give too slow and some too fast. There were aslo two many blackboard drawings, many of them were extremporized. They could have been at the sheets.

I think the audience appreciated an effort I made, the attention was not lower than for other lectures. There were quite some questions, they’ve also caught me with the hbar coefficients (no, I do not intentionally put incorrect coefficients in intermediate calculations. To confess, somethimes I intentionally do not correct then: proven to sharpen student’s attention). I’ve made a dramatic statement in the end (though did not have much time for that) to prepare the audience for the coherent state: topic of the next lecture.

 

 

Ninth lecture quantum transport

was similar to the second one. I have decided to change something and
one change lead to another one and so on. I have finished changing only
at 23:30. I know what price is to pay: a student has caught me on the third transparency. What belong to the denominator has unfortunately appreared in the numerator. Just two days ago my youngest son got a very bad mark for this. Fortunately, my title protects me from such cruel punisment.

But it was not that bad after all. In fact, I think it was rather good lecture and interesting one – at least for me. I shall improve on the derivation of antilocalization: there must be a simpler and more convincing way to express this. The analysis of experimental curves I guess was comprehensive, at least the students seem to follow. Or is this just my impression?

Had time problem: needed 10 minutes for weak localization. Usually I do not do such things, but my desire not to postpone the topic (it will not fit qubits anyhow) was so great that I asked the students to remain in the class for 10 more minutes. They have agreed. Thank you for this, and I won’ t to it again.

Seventh Lecture Advanced Quantum Mechanics

was more sucsessful than I expected. The students came in big numbers and
good mood, they were attentive and active: perhaps most have had a nice flu-less vacation. The lecture is supposed to be rather technical giving a general introduction to transitions: Fermi Golden rule, relations between emission and absorption, black-body irradiation, all that. Next lecture is supposed to provide examples, be more interesting and contain more material. This is why in the beginning I make a proposal: let’s go a bit faster, so that in the end we can eventually start with the material of eighth lecture. Not only the proposal was accepted: we really managed to do this.

There was a nice discussion around Fermi Golden Rule. It turned out that nobody knew the rule, or at least could not readily recall. Strange: former generations have had at least a vague notion of it. More improvements in bachelor education? Anyway, we manage to have really nice discussion, I guess I could bring the message about the rule, that is in odds with pure quantum mechanics but is needed to make a bridge to real world.

Another interesting discussion concerned the material of the eitht lecture.Thin emission lines, thin absorption lines: They manifest atoms. We know that our Sun consists of atoms: why its emission spectrum is continuous? Well, several years of studying physics does not automatically provide the answer, but we have manage to find one.

I enjoyed both the lecture and the audience.

Meet the rector

Our rector Jacob Fokkema has a nice attitude of talking with every prof of this university at least once a year. The form of such meetings may look rather bureaucratic: it is a 20-30 participants round-table discussion about a given topic, and one better makes homework, a short preposition about a topic. However, the rector presides with charm; he is attentive to everybody and likes to listen to opinions that differ from his own. This is why the meetings are not at all boring and often rather informative.

I attended such meeting on 10-11-2009. The topic was "University of future — future of university". I would not go into details of the meeting that were either technical or sensitive: mostly money.
I better tell about my homework. That was inspired by weblog of the rector where he reasoned about (in)compatibilities between  philosophy of open source and realities of university. (http://fokkema.weblog.tudelft.nl/2009/09/11/twittering) I began to think about, that has lead to the following (intentionally naive) presentation.

At the moment relations between a common taxpayer and universities are not quite problemless: People tend to mistrust the universities, in particular as a source of (useful) knowledge. Such broken relations have unfortunate impact on financing of the universities from public. To remedy this, and to prove their usefulness, the university scientists are requested to go to industrial partners and sell the knowledge to big (or small) business.

However: How people normally fix their relations? Well, usually one makes a gift, gives something valuable without asking any compensation. Like Prometheus did sometime ago. He did not try to sell, and his attempts to "valorise" the discovery have only resulted in chronical livercirrhosois.

There are famous and less famous Dutch people who have made a great impact (measured by millions and tens of millions users) by giving away the products of their creative work. Champions of open source. For instance:

Guido van Rossum (python programming language)
Ton Rosendaal (Blender 3d framework)
Erwin Coumans (Bullet library of physics and collisions).

Why did they do this beyond university environment? Why weren’t they employed by TU Delft so that we had Delft Python and Delft 3d Blender? Perhaps in this case TU Delft had less problems with public funds…

And perhaps it is not yet too late?

Eighth lecture quantum transport

has taken place during the official semester break. I do not know why Quantum Transport has been scheduled on this mysterious week 1.10 while Advanced Quantum Mechanics has been not. Perhaps quantum fluctuations was the reason. Anyway there were six students and I could not figure out if this number is big (for a semester break) or small (for a regular lecture).

This year I decided to swap lecture 7 and lecture 8. The reason was rather mathematical: it is handy to explain the quantum corrections with random matrix theory, the latter most naturally arises in the context of quantum dots. Unfortunately, there was a timing problem which made my presentation of random matrices rather short and incomprehensive. I cannot really understand what brought me behind the schedule. Perhaps I have spent too much time on introduction about optical dots, Eiffel tower and all that. I hardly had time to explain resonant tunnelling.

The interaction with audience was so-so. Get correct answers to my questions, while most answers came from a single student. 

 

Thanks for 16,000 views

I’ve promised to report any doubling of number of views, and I do. Thank you very much for 16,000 views! 

It’s about two month passed since the start of the blog and about two weeks since the last doubling. I did not have any comments for a long time: please, please, do comment.

 

 

Flu

Some undergraduate students wonder: why the lectures are so regular even during flu-marked months? The explanation is simple: the teachers are having flu in the semester break. I do have it almost every year: I’ve three kids at home. When I was younger, the flu usually presented a challenge, sometimes you’d defy it and go on, there was something to struggle with: headache, splitting cough, running nose at least. Now it is boring: I just feel like a squased bug, no fun at all. The brain does not seem to be affected: I was guiding phd studens per e-mail and they did not show any unrest.  So I am in full recognitionof the boredom of my existence…

This is not to complain cause I fell it’ll be OVER soon. And this is such a JOY to get back to "normal" state, the state that I normally do not notice nor am satisfied with but which is such a WONDERFUL state. Glory to God.

Citations

The merits of a primitive warrior are measured by a number of enemy scalps he/she is able to demonstrate. The merits of a bisnessman are perhaps measured by the total of his/her bank accounts, but this is usually not demonstrated. The quatifier of scientific merits is relatively easy to access, at least with TU Delft subscribtion.  You’d go to ISI web of knowledge, www.isiknowledge.com, and ask for somebody’s citation report. They give numbers that show how many times the creative works of prof. X have been cited by his/her colleagues. Nobody would pretend that this quantifies scientific excellence or usefulness or creativity of an individual. Yet the latter three are rather subjective, while the number of citations: here it is. This kind of vanity is more for mature researches, the number stays low while you work hard on your research and grows steadily while you hardly work. There is a certain similarity with a bank account.

So I consulted ISI to check the number for my favourite researcher (shamefully, his name is Yuli Nazarov). And look: I’ve found a nice round number of 6,000. Something rather satisfying: not that it is exceptionally high for my age, not that I find it corresponding to time and energy invested into recearch, yet it shows that the reasearch has been noticed.

The only phrase in the backgound of my mind irritates me, the phrase I have recently heard from a much more merited colleage : "Most theoretical papers are either cited or read". The irritation comes from the fact that I can not decide upon my papers: do I pferer them to be read or to be cited? 

It was so much simpler to demonstrate some dried enemy scalps…

Florence – Firenze

This is of course my wife to decide where to go for a vacation. Yet I could not choose a better destination to investigate the links between science and faith, Firenze citta magnifica, that has been decaying mightly for last four houndred years but has not even reached the steepest moment of decay. Thereby presenting a good example to all Western civilizations.

Take Duomo. This is a multi-functional bulding. One of the main functions is kept from tourist crowds. To access it, you need to cross several barriers: some being in your soul, some in the Duomo. For the latter, you subsequenty talk to three guards. Those are responsive, although not in English. Finally, you get close to the relics, speaking scientifically, remains of human beings preserved for veneration. For us Orhodox the most important object was the head of St. John Chysostomos.  The relics are difficult to see through jewelry of vessels and boxes. No board helps to recognize them. At some stage you  recognize that the whole Duomo
is just a shell, an outer box to keep the boxes with relics. Heavenly perfect and humaly unperfect. Perhaps this is why the Florentians hardly cared about finishing it: its facade has been a painted piece of canvas for three centuries. On a more phylosophical note: are we not just shells to keep our faith in?

And now we want more science. Hit the Museum of History of Science, by far the eldest one: it has been started in 1562. Owing to endless restauro, you can see only a third of the collection ( so the entance fee is very scientifically reduced by a third). Still there is a large amount of old sci instruments from XVI to XIX century, much more than here in Delft. Yet no the original telescope of Galileo promiced. There is another thing missed on display. By tradition of times of relative harmony between science and faith, they keep the middle finger from the right hand of Galileo. Perhaps I should have argued with the guards that I am a professor of physics and ought to venerate the remain. I did not dare and also wanted to spare my wife. She has been alreary slightly confused about motivations of researches by an eldest exposure in the museum. That was a functional celestial globe. As a detail, it is being erected by a satyr, and the globe is not the only thing the satyr has erected.

Let me finish with better example of the harmony passed. In old sacristy of San Lorenzo, the eldest church in the town, one finds a detailed fresco that reproduces stars and planets in the sky with scientific accuracy. From the planet positions one reads the date: its Jule 4, 1442. Yet the significance of the date is not clear yet: more research is needed in this direction…

Seventh lecture quantum transport

was the last in the first half of the semester.  We looked at combination of Josephson junction and Coulomb blockade to understand how one can use it to make quantum devices at home. I like the topic very much and wish the students to share my feelings. I felt indeed a bit more attention from the audience than usual.

Number of things with my presentation went wrong. The introduction into home-made quantum mechanics was too hand-waving, I felt myself loosing the logics of the explanation. Though I listed the main points, they seemed rather unlinked. To circumvent this, we turn to the formulas, and here I went too formal I am afraid. Perhaps for the next time I will have to choose a more uniform style of the presentation. The beginning of the second lecture seemed OK, but I have slowly developed a time problem. As a matter of fact, I developed time problem and could not talk about arrays comprehensively.

Though I am happy I could talk about the vortices and even get some positive feedback from the audience: did not have it years past. Perhaps a student just knew what a vortex is and helped me with this. Thank you.

We agreed that we defy the vacation and meet in three weeks. Perfect.

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