Posts in category Other funny things
Arxiv+ ?
On Thursday, Sergey Frolov has given a talk at Quantum Transport group meeting. Second half of his talk was not scientific. Rather, it was about the imperfections of modern science. I must say I initially disliked this part and even showed my dislike to the speaker. Well, there are many traditions/rules/rites in science that are obviously bad, irrational and harmful for science. Is there a point to criticize those or complain about? One could also complain about the fact that scientists must consume food and get rid of waste thereafter, thus being distracted from the research process. The efficiency of such complains would be rather low. It seems so much more efficient to regard the imperfections as external boundary conditions and silently adjust to them.
Of course, these external boundary conditions become more and stringent and one can already forsee science being totally and irreversibly replaced by priopity programs, topsectoren, european flagships and valorisation efforts. It’s too sad to forsee, this is why Sergey’s talk was so irritating. No hables de la soga en casa del ahorcado.
He even dared to criticise the back-bone of modern natural science communication, the Arxiv, calling this awing oblation effort an anachronistic mailing list and a usenet message board. I was disgusted and decided to talk to him afterwards.
This have changed my attitude. It appeared Sergey didn’t just complain: he has certain ideas and suggestions, and I must admit some of them sound quite appealing. Let me explain the Arxiv+ idea, due to Reinier Heeres an him, in a way I understand it.
A concise definition would be: a tailored collaborative framework build on the top of the Arxiv. Let’s have a large research group, an institution, a formal or informal research network of medium-to-large size. They set up a site that provides Arxiv browsing with a set of additional features: those may include annotations, comments, reminders, google-like likes/dislikes, pools, surveys, highlights… add it yourself.
Sergey has skifully provoked me to list the features I would personally like (at the level of Quantum Transport group or our institute). Here it is:
- Function for a user to tag the articles with tags like ‘spin-orbit’, ‘theory’, ‘citing QT’,’useful review’. Tag list is better supplied by admin, while the users can request an addition to tag list.
- Function to add a short comment (signed, dated) to the article like ‘I use Eq. 7 to fit my data, but do not understand its derivation, Vincent, 24-7-2013’ , ‘Cited this in my arXiv:/0789.9087, Sergey, 15-2-2012’.
- Function to do a convenient tag search like I want to see the list of all tagged with ‘spin-orbit’ and ‘nano-tube’ published in 2010-2013 in ETH.
- Naturally, tags and comments related to an article should appear whenever you navigate to the article starting from an arxiv+ window: that may be technically challenging since requires interception of http requests, yet the system would be very confusing otherwise.
- News feature: newly tagged articles, new comments upon arriving to arxiv+.
All this would be useful only if there is a substantial user activity like 5-10 tags/comments per day.
At later stage, one could consider
- Function to upload and link to an article raw data/ technical notes/ref.reports/master/PhD theses (local storage should be arranged, requires a permission settings feature), extremely useful on a long time-scale.
- Function to make user-specific collections with user-specific comments (if this function is provided from the beginning, no collective effort would ever emerge)
- A convenient interface to journal version.
Do you have a feature idea? Please do not hesitate to comment on this or write to Sergey directly.
Bas Hensen
graduated today. He did it in the group of Ronald Hanson, quantum physics of diamonds, today and I was a member of graduation commission.
In course of the event, Bas Hensen has surpised me a number of times, perhaps more than any other graduating student I recall
- He is a sucsessful example of “taking graduation in his/her hands”. He came to experimental group, and said he would do “theory”: actually, a design of a new experiment. He never took a screwdriver. Nevertheless, the group was very pleased with his work.
- His thesis contained, among other things, a fairly complete outline of group theory typed by him personally (not just cut-and-past from a source)
- The topic concerned producing entanglement by measurement
- He knew that I always ask the students about rainbow. My impression was that nobody has noticed that.
Professors wanted in Delft
Our small department seeks to expand, and, for a change, a sucsessful candidate may be a theorist. The advertisment of the job openings is now official. I’ve spent quite some time today propagating the announcement via my network, before I understood that I can just blog it
Here it goes:
The Department of Quantum Nanoscience, part of the Kavli Institute of
Nanoscience at the Delft University of Technology opens 2 positions of
PROFESSORS
(assistant, associate or full)
in Quantum Nanoscience
The department
The department of Quantum Nanoscience, part of the Kavli Insitute of Nanoscience at the Delft
University of Technology seeks to advance the understanding of physical processes at the nanoscale,
with a focus on research for fundamental scientific and technological breakthroughs. Our approach is
based on quantum engineering, in which we develop innovative nanofabrication, innovative
measurement techniques and advanced theoretical models. Our ambition is to create an
interdisciplinary research environment, in which scientific staff and students explore, learn and teach.
With the Kavli Nanolab Delft the department is equipped with an excellent, state-of-the art
cleanroom.
Job description
The department invites applications for two professors in Quantum Nanoscience. The candidates are
expected to be, or on their way to become, authorities in their own field of research, which preferably
complements and/or enriches the existing research programs in the department. Hiring is on the
basis of the excellence. The new faculty members are expected to establish and execute an
externally funded, research program. Teaching is primarily at the undergraduate and graduate level
in the Applied Physics curriculum. For the PhD level teaching is carried out in collaboration with the
University of Leiden through the Casimir Research School. External funding should be sought on the
(inter)national level and professors are encouraged and assisted to apply for competitive personal
research grants. Candidates are expected to have the organisational and managerial skills to interact
and cooperate effectively with other research institutes and organisations.
Requirements
Candidates have an excellent track record in scientific research, as evident from papers in
international and peer-reviewed journals. Applicants are inspiring teachers with good communication
skills and interdisciplinary interests. Applicants hold a PhD degree in physics or a related discipline.
The Delft University of Technology is a bilingual organisation; an excellent command of English
(written and spoken) is essential. Learning the Dutch language upon arrival is encouraged.
Conditions of employment
Assistant candidates will be appointed on a tenure track with the prospect of a tenured position based
on a successful evaluation after 5 years. The Delft University of Technology strives to increase the
number of women in higher academic positions; women are therefore especially encouraged to apply.
Information and application
For more information about these positions, please contact the head of the Quantum Nanoscience
department, Professor H.S.J. van der Zant, h.s.j.vanderzant@tudelft.nl. To apply, please send a
detailed Curriculum Vitae along with a letter of application and an one-page research statement to
drs. M.P. Swarte, M.P.Swarte@tudelft.nl. More information about the department can be found on
www.qn.tudelft.nl.
We will continue our search until the positions have been filled and no strict application deadline has
been set. The starting date is flexible but is expected to be in 2012.
Enquiries from agencies are not appreciated.
Topology and physics: a new conjecture
When I was a student, we were all fascinated by first steps the topological approach made into physics. It took a while to understand that the winding of phase around a vortex is always 2π whatever you do; and that had a sweet taste of intellectual victory. We all read review of Mermin : it was so enlighting to learn that even π in topology has a different, much more profound meaning of homotopy group.
Topology has progressed in years gone, and overwhelms in recent years. There are no more insulators: we’ve topological insulators. They insulate as wet towels, yet are much more profound. The advent of topological superconductors has revolted the field of superconductivity that seemed so stable. And no quantum computing scheme would ever work if topology does not give its protective blessing.
In a kind of conservative rebellition I suggested on Saturday in my talk that perhaps there may be some interesting things in physics that are not based on topology of coordinate space. O boy, how wrong I was. My only consolation is that my wrongness let the truth prevail.
Today Charles Marcus, a Harward professor and most intellectual experimentalist I know, has responded to my talk with a seminal conjecture that I have a great honour to publish.
Marcus’s conjecture
Any result involving integers, including 1 + 1 = 2, can be represented geometrically as a statement of topology, since 1 + 1 = 2 cannot be continuously deformed into any other relation between integers.
Breathtaking. I could have suspected so, why was I so blind…
A note for non-specialist: physics originates from, and is based on counting fingers. For all practical purposes, the result of such counting can be approximated by an integer non-negative number. The conjecture therefore puts physics into the true context: it appears to be a practical exercise in homotopy theory.
A technical note: Charles insisted on presenting his conribution as a conjecture, while the proposition clearly has the status of a theorem. He said he would not present the proof yet. I wonder how he has actually done the proof yet concealed. Being a physist, he could use the traditional medium of this profession, the backside of an envelope. Having understood the importance of topology, he could turn to a margin of a Greek manuscript, the only proper medium for seminal mathematical discoveries since Fermat. Being a conservative rebel, I’m just exploring the consequences of occasional and absolutely unintended dissapearence of this envelop/manuscript. What a wonderful lost for science could it be!
Col Vert
yesterday there was a free afternoon at the conference. People get to the mountains, so did I. My traversal speed was quite low and I did not feel well. Yet after two difficult hours I reached the goal: pass Le Col Vert in Vercors.
It was magnificient. The pass is very steep and narrow. When after a hard walk I was able to see the next valley, I was overwhelmed with pure joy of detachment. Me or my soul or both have been freely flying over the unbelievably beautiful sunny landscape.
This is the second time I’ve reached this pass. First time it was more than 11 years ago, and the path was significantly less steep:) By that time I could also enjoy this detachment feeling, yet I could not inteprete it. Now I know: there are some places on Earth that directly and evidently put us above the earthy events. Glory to God.
Blog dirty superconductor workshop
blogging is a must today, almost the only way to prove somebody’s existence: “Bloggo ergo sum”, as Descartes would put it today. So we in this dirty superconductor workshop also have an extensive blog, here’s the LINK
.
Below is my post to this blog: report on one of the talks.
Vladimir Kravtsov: Electron cooling rate in amorphous films near superconducting-insulating transition
What can we learn from the giant I-V jumps experiments?
The talk presented overwiev of the work made in collaboration with B.L. Altshuler, V.E. Kravtsov, I.V. Lerner, I.L. Aleiner in response for experimental
findings of M. Ovadia, B. Sacépé, and D. Shahar. The experiment has demonstrated a set of hysteretic I-V curves with order-of magnitude jumps and spectacular temperature dependence. It turned out in 2008 that these curves in all details can be explained if electron overheating is taken into account.
An ultimately simple and elegant phenomenological theory is based on a single equation:
IV= joule heating = cooling rate of electrons to phonon bath, and takes as input the linear temperature-dependent resistance R(Te). The speaker outlined the details of the theory demonstrating its sensitivity to the assumptions concerning the temperature dependence of the resistance and cooling rate presenting several simple solution. Further, he concentrated on the coolest part of the story: temperature-dependent electron cooling rate!
He mentioned that the experimental evidence of strong decoupling of electrons and phonons in insulators undermines usual assumptions that the phonon-assistant electron hopping is the dominant transport mechanism in insulators. The temperature dependence extracted from the experimental data clearly demonstrates the rate proportional to T^6 at hight magnetic fields. T^6 law has been derived for common metals yet by Albert Schmid in seventies. It is somehow puzzling that the proportionality coefficient is 2-4-5 orders magnitude larger than the theory of common metal would predict if extended to localized states (the precise number of orders of magnitudes depends on the estimations of sound velocity). The computation of the coefficient for localized states requires more attention but the power law seem to hold: the speaker argued that the fact that the electron states are localized should not by itself lead to Arrhenius law in temperature dependence.
The most dramatic part of the talk concerned the cooling rate extracted from yet
unpublished data at low magnetic fields. The data did display Arrehius law with energy gap of 1.75 K. The speaker argued that this is a clear manifestation of preformed localized electron pairs in the material. He outlined general problems with forming such pairs in insulator if Coulomb interaction is taken into account. He made use of analogy with double-ionization to assure himself and the audience that Nature permits such things.
The talk provoked a discussion that has started slowly but soon become overheated and
involved multiple parties. Sasha Finkelstein has asked a question about phonon-assistant hoping and expressed his surprise with low energy scale invloved
that is in apparent contradiction with Coulomb energy estimations. The blogger wondered why the cooling rate was assumed to be such a simple function of two temperatures. The answer was that this form was obtained yet by Schmid but eventually
has no apparent reason to be general. Misha Gershezon has shared his experience in measuring colling rates and posed a series of questions addressed to experimentalists and concerned with time scales of cooling. Zvi Ovadyahu mentioned that overheating bistability is readily observed at room temperature. Why does one have to go to low temperatures? The answer: to get cooling rate at low temperatures.
The discussions in groups have lasted at least half an hour after the talk.
Re-flows on arxiv
,finally. I’m quite proud of and excited by the paper. The excitement was so high that I’ve been working yesterday the whole day on the text, fixing small things, but, quite embarassingly, have completely forgotten to run it through a spell-checker… Oh.
Here’s the LINK.
The abstract is rather long:
We demonstrate that the condensed matter quantum systems encompassing two
reservoirs connected by a junction permit a natural definition of flows of
conserved measures, Renyi entropies. Such flows are similar to the flows of
physical conserved quantities such as charge and energy. We develop a
perturbation technique that permits efficient computation of Renyi entropy
flows and analyze second- and fourth order contributions. Second-order
approximation was shown to correspond directly to the transition events in the
system and thereby to posess a set of “intuitive” features. The analysis of
fourth-order corrections reveals a more complicated picture: the “intuitive”
relations do not hold anymore, and the corrections exhibit divergencies in
low-temperature limit manifesting an intriguing non-analytical dependence of
the flows on coupling strength in the limit of weak couplings and vanishing
temperatures.
Unphysics of quantum information
rocks. I’ve just finished my major contibution to the field: paper on flows of Renyi entropies.Will put in on cond/mat in several days.
111
My grandfather Aleksei Ivanovich Nazarov would turn 111 years old today. He has lived 82 years. I always admired the degree of change that took place in society in the course of his life span. He’s born in a poor peasant family. He and his brothers and sisters did not get any shoes till they got ten years old. He died in postindustrial society where the first personal computers just become accessible. If I project the change during my life span, I find it bigger than pleasant, yet much smaller than he has experienced. Or perhaps the projection is just wrong? Or perhaps I’m yet to see my grand(grand)children walking barefoot.
FQMT11
that is “Frontiers of Quantum and Mesoscopic Thermodynamics” was a relatively large conference in Prague where diverse aspects of quantum mechanics have been discussed. It has been organized (mainly) by Theo Nieuwenhuizen and Václav Špička. It’s been long I was at such broad yet interesting conference that covered everything from black holes to biomotors and I enjoyed much. Ciprian and Frans were also there. Many talks (hopefully, including mine) were inspiring and I was able to get new ideas and finish some hard calculations.
The plot of the organizers was to habituate us to everyday portion of classical music so that we get use to it, develop an addiction and will attend further conferencies in series. This has worked quite well, I must admit. Being a Slav, I could appreciate typical Slavonic hospitality that stems from the deep of the heart, may look clusmy and eccentric, yet leads to unusual and memorable experience. To give an example, we have been welcomed by His Eminence Dominique Duka, Archbishop of Prague, in his seat cathedral and were allowed to get intoxicated in Senat of Check Republic.
Many thanks, Theo and Václav, we look forward to the next conference like this.