Posts in category Education

was a change of the topic: we have departed from the scattered quantum waves and entered the world of Coulomb blockade.  I have stressed from very beginning that this is perhaps a boring world, although I myself do not think so. However, I am afraid I was boring at times. Perhaps it was just a matter of mood.

The slides of the lecture, especially the diagramms in the slides are better be updated to match the book. I did not to it this time to avoid, according to the mechanism described earlier, a complete rewritting of the lecture. I would do it next year.

This was I guess the majour problem while taking about co-tunneling. I was trying to explain a cartoon, while the sildes give formulas. That gave this discrepancy between the speech and visual and was bad for explanation.

was difficult and somewhat technical. Hopefully, it was not boring since I’ve been trying all side stories to keep the audience attending. Besides the material, the microscopic theory of superconductivity being the main topic of it, traditionally interests students. 

There are still many students, more than in years past. They also react differently than in the past. For instance, I used to encounter resistance when coming to work whithin a single Nambu cell, I was requested and had to write the wavefunction as a 2-vector and act with 2×2 matrix thereupon. Today I did not get such request, the students seem to follow. However, just by inertia, I wrote 2-vectors and 2×2 matrix at the blackboard… I’ve thrown a question about contact interaction in completely polarized electron gas where it cancels because electrons cannot come close to each other. Actually, in the past the answer to this question used to come quickly, immediately after the hint that they do not come close to each other. Today there was a significant delay… Why? Luckily, the answer has emerged after a while. A similar question — where did the factor 2 go? — has been answered a way too quickly. So I suspect telepatic abilities in a part of the audience.

As to my telepatic skills, I have to brush them. Close to the end of the lecture, I began to hear very distracting noises from the adjacent room. Bet most students did not hear that and wondered about the reason of my distraction. I tried to send a telepatic message to the noise source. No avail, I had to break the lecture and appear in person. There were four young gentlemen enjoying table soccer match.  While apparently surprised by my request to do it queiter, they were kind enough to accomodate it.

I still have to decide what to do with superfluidity. It looks like I will have to combine with classical description of electromagnetic field. In this case, that’s going to be a mjour pedagogical innovation: do not miss it!

was the one I was afraid of.  First of all, the material was a bit "dry" many formulas, although simple ones, less stories to tell. Second, similar to the second lecture, I made rather big changes in the slides and not really in advance. In fact, I have finished the changes at 2 a.m. today.

After all, the lecture have not gone too bad. Or is this just illusion? I was reasonably well on time. In fact, I had to brake in last 15 minutes. There were questions and answers, although not that much I would love. I was a bit dissapointed that nobody answered a control question: what is the combination of two diffusive  conductors? I thought I have said enough to provoke the answer…

I guess the number of students has stabilized, I am with core supporters.

was a fulfillment of duty. Most material given was quite difficult to follow, especially at the pace of the lesson. Also it is the most difficult chapter of the book. An easy solution would be just to talk about something else. Or present the topic only partly, just concealing the sharp edges and not drawing conclusions that wait to be drawn. If I do so, I would not be a scientist in a way I understand it. It is my duty to tell about this spectacular line of reasoning that starts from Gustav Kirchhoff, goes through treasures of and ends with curcuit theories of quantum transport. I am afraid if I do not give it nobody would. And this line of research will die replaced by primitive meso-nano-pico-amto incidentalies.

So suffered I, so students did. The first part of the lecture (double junction revisited) get eventually rather good, still felt interaction with the audience. The third (double junction again) was, to my understanding, yet easy to follow. Second (the road from quantum to classical) and forth (quantum circuit theory) are disastrous. I was trying to appeal to previous knowledge, to common sence, to anything: still was hard. Anybody can give me hints?

The student numbers are dropping, how many will I count next Friday? Good news come from problem-solving session of Ciprian. There were many, and many have attempted doing homework.   

was a hard one. Today we have switched from "technical stuff" of second quantization to applications: Magnetism. Something about history of teaching attitudes. I have inherited this course years ago from prof. J.J.J. Kokkedee who gave it since 1970, I reckon. The latest "dictaat" of Kokkedee course can be found at the Blackboard. When inspecting this, one finds many similarities in contens. This is natural, because the fundametals of physics have not changed since that. What has changed is the teaching attitude and approach to student — taken the personal differences apart. Namely, the material of the lecture about magnetism was given to students at the exam: just a problem to solve. Modern education is decisively different. Roughly, the students of that time have been taught to less things, but have been expected to know more and to cope with more. A quick pseudo-logical conclusion would be: the students of the past were better prepared and in command of a superior intellengence. Let me say: negative, this is not so, in many cases it is (was) the opposite. Yet the further attempts to comprehend this would lead us to even more paradoxical conclusions, decisively more paradoxical than quantum concepts…

Back to the lecture. The timing was close to the ideal schedule: I was a bit double-crossing in the beginning when announcing the intention to finish the magnetism. Former experience shows that it could go worser: twice I was able to deliver only the second quantization for fermions. Today we stopped just on time: we have stumbled upon a technical problem discussing magnetism, got a prescription to deal with. Homework would do the rest.

Of course it was a bit too fast, I apologize. I hope you appreciate my good intentions. I was trying to tell about many things at once, my speech occasionally got erratic indicating the wandering mind. Must be irritating: Best way to stop it is to shoot a round of questions. Do me a favour.

Before the lecture got a question about my origin. In case more are interested: I was born in Siberia and dwell in the Netherlands since 1993, all time employed by TU. Suppose you like trains. Are you aware of possibility to travel from Amsterdam to Beijing changing trains just twice? If you take this challenge, you’ll pass my native city on the fourth day.

Was embarrasing for me. Was told many times by experience teachers that one should not prepare for the lecture and withstand this tempation provided it arises. Because in this case you want to improve the lecture, thus making changes, thus making errors, thus getting caught afterwards. No use. So I was caught by two students simultaneously: thanks to them for being attentive and bringing the issue.

The start was not very encouraging. A minute before the start I saw only few students that defied all laws of statistical distribution by filling the least probable back rows. Fortunately, it dramatically changed at mere last moment. I was even able to address the audience "ladies and gentlemen" while have already prepared for "gentlemen". Still: two first attemps to get a response from the audience were not accomodated. Luckily, it got to normal a bit later.

The changes made were intended to bring the lecture slides close to the book and to give more physical significance to the phase shifts. First part, multi-terminal scattering, remained almost intact. In future, I shall find a way to present it faster and in a more interesting fashion. It appears I need more time for interference, second part. Although I’ve spent only 4 minutes joking, I have had an acute time problem and finished at 12:33 only.  Sorry, never again. The story "A and B" has been improvised and upon my taste was usefull to illustrate the interference, but I haven’t checked it against other tastes. Please comment on this.

The events of yesterday, in particular the party, have significantly impeded my teaching abilities as well as willingness to teach. But there are things men must do, so I stood up and was on time in the class.

I started with an honest promise that it will be the most boring lecture in the course. They laughed in disbelief, but I guess I managed to convince them pretty soon. Indeed, the lecture is very technical, and the need of all these technicalities is very difficult to assess without applying those many times. I could only state: bear with me, this is important, makes sense, just wait a week or two. This is how we get through the CAPs, field operators and confusion of the second quantization. It is a meaning of this lecture after all to create a feeling of certain confusion, unsatisfied understanding: what are all these funny things for? It will get easier in a week when we will do the same for fermions and at least repeat the stuff.

The contact and feedback is still good. There were questions, although most of them come from three male students in the class. If I only hear correctly, one always calls me "sir". This does not quite fit my democratic convictions, but I don’t dare to correct him, I like him questioning. After all I have an officer rank, though that of army forces of a non-existing state. A question from another student was a real hit: he managed to follow dimensionality of the resulting expressions, revealed a problem and made everybody attent of that (different dimensions of a quantity and its Fourier transform). The audience also responded well to my questions. When I asked if more explanations are rwequired, the answer was quick and positive.

I did therefore more side explanations than last years. By some good magics, I manage make all in time (though I had to go through Fock space that remained from the first lecture). Bad side of it is using side panels of physical blackboard. Bad writting, oftenly not visible to all students, sometimes confusing notations. Last year I wanted to solve this problem by advanced techiques: I made use of a digital tablet where my writtings were directly projected onto the screen. I do not do this this year because of the problems I had. First hardware: I had to bring the tablet along with the laptop and connect six cables, in most cases yet to reboot computer and adjust the resolution to get it working with the tablet. Second, sofware: from time to time, it gave a buffer overflow and there was always a chance that the writting dissapears before it is finished. Third, me: computer pen is slower than chalk and requires better control, one who forgets about writes as a pre-pre-school kid. I don’t know what to do: perhaps I have to find just better software and hardware (better me does not seem a feasible option).

For those who could be offended/confused by explanation about creation/annihilation operators: I’m a Christian, I do believe that (cross) death is a new beginning, no joke is meant.

To summarize, I’m reasonably satisfied with the lecture. How about you, the reader? Still nobody comments …

Took place today. It has been scheduled directly after the lecture of Herre van der Zant on "physics at NanoScale" , in the same room. Handy! The students can follow seemingly similar courses in the same place and time. Indeed, almost a half of the students just remained seated. Given circumstances, I start the lecture with explaining the difference between the courses. I did it at rational level of course without going into historical details about mesoscopics and Kees Harmans. I have a feeling that the students appreciated the explanations. Actually, I’d love students attending both courses: it does not happen that often in the course of the whole education that they are given two different, complementary views at a set of topics.

Number of students again roughly corresponded to Blackboard data. I could not beat temptation and actually counted them after the break (to reduce statistical error). That came to 18: 85% of Blackboard number. Let us hope I can keep them all.

The audience had, on my estimation, 50% overlap with that of Advanced Quantum course. I should eventually check this: it can become important. Again, in comparison with the last year the audience was decisively more active. Imagine, I get a question from a "native" student during the FIRST lecture! This is the second case in the course of my service at TU. Another impression – let me formulate it like this – the audience is more mature. And more open for less common things. Close to the end, we have to vote. I had too little time to talk about counting in detail and ask them to choose if we shift the topic to the second question. They vote fast and without hesitation. So I had to gabble the last fifteen minutes:)

Again I was a bit edgy about new audience and put too much jokes and side stories. It was supefluous to mention Tolstoy: he deserved better occasion. There was too much about winding coils in the beginning: guess they got it from the first run. All these side stories costed time: therefore this gabbling about counting. Volgende keer better.

A worrisome point. Felt less contact with audience while presenting elementary wave mechanics. Plane wave, statistics went fine. The stress become to mount at waveguides. One-dimensional motion with a barrier: most faces got surprised. Did they get it during the bachelor course? In case it has been skipped from the bachelor, I really must protest. There must be limits to profanation of quantum line in Delft. Anyway, if this piece of knowledge is absent, it is all on me. Is it a good idea to include it in home work? In Advanced Quantum, we do not hesitate to refresh the elementary quantum with home work. Then it could be an extra set of problems, perhaps 2. I ask the readers of the blog to react to this proposal.

And final point about being edgy and interactivity. I have not erased the (physical) blackboard. Somebody did it for me. There was the URL of this blog at the blackboard. If this person reads me: many thanks and an apology.

Has happened today. There were almost as many students as Blackboard has predicted. Actually did not count them. Introduced Alina and she received an enthousiastic response (despite a realtively short appearence).

The audience is visibly more active than a year ago. Any time I was asking for a response, I was getting some. A hypothesis: this is a function of student density. When students are close to each other, they are less likely to fall asleep and thus follow the lecture. As to questions: we did not get that far. The questions usually come from international students, and it seemed that there are no many of them this year.

I’m afraid I was also slightly over-excited and put too much entertainment. The response to this was mixed. Perhaps because of jokes, was out of time for the Fock space. Anyway this topic suits more the lecture #2.

There were many organizational questions after the lecture: eventually, much more than in years past. There may be a sort of of misunderstanding. I am going to post a message at the Blackboard to make sure everybody knows the answers.

To summarize, I met a reasonably active, inspiring audience. However, I still have to adjust to it.