Interdimensional confinement as a route to exotic phases of matter.

KTH/Nordita/SU seminar in Theoretical Physics [before December 2013]

Wednesday 22 June 2011
from 11:00
to 12:00 at
122:026

Speaker :

Carlos Bolech (Univ. of Cincinnati)

Abstract :

A series of experiments on systems of trapped cold atomic gases were aimed at studying the effects
of polarization on superfluid pairing. Two different experimental groups encountered surprising
qualitative and quantitative discrepancies which seemed to be a function of the confining geometry
and the cooling protocol. Despite long familiarity with fermionic superfluids, these observations
had defied theoretical explanation. Using novel numerical algorithms we study the solution space
for a three-dimensional fully self-consistent mean-field formulation of realistic systems with up
to 100,000 atoms. Our studies demonstrate a tendency towards metastability as the geometry is
elongated and suggest an explanation for the observed discrepancy. From our calculations, the most
likely solution which is consistent with the experiments at high aspect ratio supports a state
strikingly similar to the so called FFLO state (after Ferrell, Fulde, Larkin and Ovchinnikov),
which had been theorized but eluded detection so far. Moreover, this scenario is consistent with
the predictions for one-dimensional systems of dilute polarized attractive gases, and yet another
set of cold-atom experiments use optical lattices to test this limit. The measurements are in
quantitative agreement with theoretical calculations (using a wide array of numerical and analytic
techniques) in which a partially polarized phase is found to be the 1D analogue of the FFLO state.
More calculations and experiments are under way, testing the inter-dimensional stability and
crossover.