R. G. Herb Condensed Matter Seminars

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Events During the Week of October 15th through October 22nd, 2017

Monday, October 16th, 2017

No events scheduled

Tuesday, October 17th, 2017

No events scheduled

Wednesday, October 18th, 2017

No events scheduled

Thursday, October 19th, 2017

Cyclotron resonance in graphene: Kohn’s theorem, many-particle physics, and more
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Erik Henriksen , Washington University in St. Louis
Abstract: Cyclotron resonance—the resonant absorption of infrared light by charge carriers in a strong magnetic field– is one of the more basic measurements that can be made on semiconductors. First demonstrated on germanium in the early ‘50s, CR proved to be enormously useful in determining semiconductor band structures and, from the ‘70s, was instrumental in probing two-dimensional systems in Si and GaAs heterostructures. However, early on W. Kohn pointed out a limitation of the CR technique: in translationally invariant parabolic systems, CR is insensitive to electron-electron interactions, with the consequence that CR has been useless in investigating such remarkable phenomena as the fractional quantum Hall effect. We have performed CR measurements over the past decade that demonstrate how to evade Kohn’s theorem by breaking translational invariance, or working in graphene whose linear dispersion can be viewed as an extreme case of a non-parabolic band structure. In our most recent work we find direct evidence of many-particle physics in the cyclotron resonance of high mobility graphene. This exciting development suggests that infrared spectroscopy will provide a new window on interacting electron phenomena in graphene including (fractional) quantum Hall effects, Hofstadter’s butterfly, hydrodynamic transport, and perhaps even cavity QED.

Host: Brar
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Friday, October 20th, 2017

Ultra-high Q Superconducting RF Cavities: from particle accelerators to quantum computing
Time: 11:00 am
Place: 5310 Chamberlin Hall
Speaker: Alex Romanenko, Fermilab
Abstract: “Superconducting radio frequency (SRF) cavities are an enabling technology for all modern accelerators where they serve as a primary means to accelerate charged beams. Extremely high quality factors Q=10^10-10^11 of SRF cavities in the broad range of fields up to tens of MV/m allow continuous wave operation of accelerators for various applications, i.e. SNS, CEBAF, LCLS-II, PIP-II and others, as well as make SRF cavities an attractive option for various non-accelerator applications ranging from quantum computing to dark sector photon searches. In this talk I will review the underlying science achievements and challenges in SRF, as well as describe the new SRF ‘quantum’ regime effort at Fermilab.”
Host: McDermott
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