1 / 2

2011 Highlight: Outreach Anthony J. Leggett, University of Illinois, Urbana-Champaign, DMR 0906921

Highlight 2011: Topics in Ultracold Fermi Gases and Topological Quantum Computing Anthony J. Leggett, University of Illinois, Urbana-Champaign, DMR 0906921.

astra-nolan
Download Presentation

2011 Highlight: Outreach Anthony J. Leggett, University of Illinois, Urbana-Champaign, DMR 0906921

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Highlight 2011: Topics in Ultracold Fermi Gases and Topological Quantum ComputingAnthony J. Leggett, University of Illinois, Urbana-Champaign, DMR 0906921 For 40 years it has been recognized that below about 1 degree absolute the properties of almost all amorphous materials ("glasses") are not only qualitatively similar (e.g. the specific heat is almost always approximately proportional to temperature) but show a truly amazing degree of quantitative universality. In particular, the dimensionless transverse ultrasonic attenuation Q-1 is, almost without exception, equal to 3*10-4 to within a factor of ~2 for a wide range of materials of very disparate structure and composition. To the best of my knowledge, explanations of this phenomenal degree of universality in the existing literature have rested either on experimentally untested (and usually untestable) assumptions about unobserved properties of the systems in question, or on invocation of the dubious phenomenological ansatz known as the "tunnelling two-level systems" (TTLS) model. With Dervis Can Vural (supported by the grant, formerly as a student and currently as a postdoc) I have been able to show* that, given two currently unproved but plausible assumptions, a very generic model of amorphous materials – far more generic than the TTLS picture – automatically leads to a small and quasi-universal value of Q-1; and with one further plausible assumption, that the numerical value is close to that observed experimentally and the frequency-dependence in at least as good agreement with the data as existing theories. The basic mechanism is the virtual-phonon-induced interactions of the stress tensors of large blocks. We are currently trying to tighten these arguments so as to produce an upper limit on Q-1 for any solid material, whether crystalline or amorphous. *J. Non-Crystalline Solids 357, 3528 (2011)

  2. 2011 Highlight: OutreachAnthony J. Leggett, University of Illinois, Urbana-Champaign, DMR 0906921 I have been much involved in outreach activities at various levels over the last few months. During a tour of India in January 2011 I gave a total of 19 lectures, many of them to undergraduate audiences, including four out of the five recently established IISER's. In April I gave an inaugural address to the incoming graduate students of Tokyo University (a rather special event this year, since it took place only a month after the Great East Japan Earthquake). In the summer, during a two-month stay at the University of Waterloo, I gave weekly mini-lectures on superconductivity (with demonstration) to grade 5-6 school children. Finally, in the fall of 2010 I took part in the UIUC "Physics Table" at the local farmers' market, answering questions from local citizens young and old (see photo).

More Related