Fall 2013 Upcoming Colloquia*
September 9
Speaker:
Allen Caldwell, MPI Munich
Title: "The Search for Neutrinoless Double Beta decay"
Abstract:
While the the standard models of cosmology and of particle physics
impressively explain the bulk of the observations made to-date, some key
questions still await answers. Amongst them are the reason for the
matter anti-matter imbalance of the universe and the fundamental
description of neutrinos (e.g., are they their own antiparticles ?).
The search for neutrinoless double beta decay is motivated by these
larger questions, and the observation of such a decay would be a
milestone in the development of our understanding of the universe. An
introduction to the topic will be given, followed by a description of
the GERDA experiment, an experiment that searches for neutrinoless
double beta decay in Ge-76.
September 16
Speaker:
Jim Eisenstein, Caltech
Title: "Exciton Transport and Perfect Coulomb Drag"
Abstract:
A key attribute of typical quantum Hall systems is that they are
topological insulators: They are electrical insulators in the bulk even
though perfectly conducting chiral edge states lie at their boundaries.
Most quantum Hall effect (QHE) experiments employ a simply-connected
Hall bar geometry in which all current and voltage contacts lie at the
sample’s boundary and are thus connected to these edge states. Such a
geometry is sufficient for observing the vanishing longitudinal and
quantized Hall resistances which are the hallmarks of the QHE. In
contrast, multiply-connected geometries, such as a Corbino annulus with
contacts on the inner and outer boundaries, provide clear demonstrations
that the bulk of the 2D system is indeed insulating.
In this talk I will discuss how a certain bilayer quantized Hall state
modifies this scenario. Specifically, I will report the results of
recent experiments in Corbino devices which clearly demonstrate that
while the bulk of the bilayer quantized Hall phase at total Landau level
filling factor v = 1 is an electrical insulator just like any other
quantized Hall system, it is nonetheless possible to transport energy
across it. I will show that this energy transport is enabled by the
flow of charge neutral excitons across the bulk, with their emission and
absorption at the edges taking place via Andreev reflection. In a
closely related ongoing experiment, we have shown that a current
flowing in one 2D layer can induce an equal, but oppositely directed,
current in the other 2D layer even though there is no electrical
connection between them.
September 23
Speaker: Doug Stone, Yale
September 30
Speaker:
Andrei Gruzinov, NYU
October 7
Speaker:
Chuck Hailey, Columbia University
October 14
Speaker:
Dimitry Basov, UCSD
October 21
Speaker: Mark Halpern, University of British Columbia
October 28
Speaker:
Alberto Morpurgo, University of Geneva
November 11
Speaker:
George Sawatzky, UBC
November 18
Speaker:
Nadya Mason, University of Illinois at Urbana Champaign
December 2
Speaker:
December 9
Speaker:
December 16
Speaker:
