Fall 2019

From solids with topology to black holes and back

Marcel Franz
Monday, December 2, 2019 - 4:00pm

Inclusion of topological phenomena in condensed matter physics over the past 10 years ushered a new era in this field. As a result of the groundbreaking theoretical insights entire new classes of materials with exotic properties have been discovered, including topological insulators, Dirac and Weyl semimetals as well as topological superconductors containing Majorana fermions. In this talk I will review these developments and discuss an intriguing connection noticed recently by Kitaev between one such topological system – the Sachdev-Ye-Kitaev model – and the horizon of a black hole. This...

Measuring the entropy of a single spin

Joshua Folk
Monday, November 4, 2019 - 4:00pm

Entropy measurements offer a powerful tool for identifying the underlying microscopic character of electronic states.  Such measurements are typically based on bulk properties that are straightforward to observe in macroscopic samples, but exceedingly difficult to access in mesoscopic systems that may consist of just a few electrons or quasiparticles. Taking advantage of a well-known Maxwell relation, we realize a protocol for entropy-to-charge conversation in a gate-defined GaAs quantum dot that enables an entropy measurement of the first three quantum states in the dot. The entropy of a...

Anomalous Velocity and Geometry in Wave Mechanics

Eugene Mele
Monday, October 7, 2019 - 4:00pm

In electronic band theory the dynamics of electrons in crystal lattices can exhibit novel phenomena associated with the anomalous velocity. Modern work on this subject revives an idea which appeared in its primitive form some fifty years ago to interpret the anomalous Hall effect in magnetically ordered states of matter, namely the appearance of a Hall conductivity in materials that have spontaneously broken time reversal symmetry without an applied magnetic field. The signature of the anomalous velocity is the coupling of electron motion to applied static and time-dependent fields through...

SEISMIC: The Sloan Equity and Inclusion in STEM Introductory Courses Project

Tim McKay
Monday, September 23, 2019 - 4:00pm

Equity and inclusion are important goals for higher education. Data can play a central role in achieving these goals. First, data are essential for probing equity. To provide an example, I will describe the discovery of a pattern of gendered performance differences in large foundational courses, both at Michigan and at an array of other Universities. Data can also help create solutions, as when we test new course designs and develop tools that personalize education. 
Over the last year, a group of ten large public research universities have launched the Sloan Equity and Inclusion in...