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Events on Friday, March 7th, 2014

R. G. Herb Condensed Matter Seminar
Experimental review on the disordered-driven superconductor to insulator transition
Time: 10:00 am
Place: Chamberlin Hall
Speaker: Daniel Sherman, Bar-Ilan University, Ramat-Gan, Israel
Abstract: The disorder-driven superconductor to insulator transition (SIT) is considered to be a prototype of a quantum phase transition at zero temperature. Lately, there has been a renewed interest in this field due to the experimental observations of a number of dramatic features near the SIT of amorphous superconducting materials such as indium oxide and niobium nitride. These novel features included the simple activated temperature dependence of the resistance in the insulating side, a large peak in the magneto resistance, peculiar I-V characteristics and traces of superconductivity at temperatures above Tc. We present experimental results from tunneling spectroscopy, Terahertz spectroscopy and transport measurements that shed light on the physical mechanism governing this phase transition. Our key observations are: 1 - Superconducting gap in the insulating side of the transition. 2 - A possible experimental evidence for collective modes (namely the "Higgs" amplitude mode) in such disordered films close to the SIT. 3 - The possibility to tune the quantum phase transition simply by screening the e-e interactions. These results and their possible consequences will be discussed.
Host: Mark Eriksson
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Physics Department Colloquium
Verner Suomi’s Vision with a Spotlight on Benchmarking the Earth’s Climate from Space
Time: 3:30 pm
Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
Speaker: Hank Revercomb, UW-Madison, Space Science and Engineering Center
Abstract: The talk combines a summary of satellite observations for weather and climate that have followed from the vision and pioneering developments of UW Madison’s own “father of satellite meteorology,” Verner Suomi, with a description of a new approach for benchmarking the Earth’s climate from space. The second half features the Absolute Radiance Interferometer (ARI) instrument, developed to provide benchmark measurements of Earth emitted radiance (3-50 microns) with a brightness temperature accuracy of 0.1 K (3-sigma). The key feature of ARI is the new approach it employs for on-orbit accuracy verification. Along the way, you will be introduced to the UW Space Science and Engineering Center, a Graduate School center co-founded by Verner Suomi that is part of his vision.
Host: Lawler, Timbie, Nossal
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