BEGIN:VCALENDAR
VERSION:2.0
BEGIN:VEVENT
SUMMARY:Emergence of coherence in an uniform quasi-two dimensional Bose gas
DESCRIPTION:The dimensionality of a system strongly affects its physical properties;  the phase transitions that take place and the type of order that arises depend on the dimension. In low dimensional systems phase coherence proves more difficult to achieve as both thermal and quantum fluctuations play a stronger role.  The two-dimensional (2D) Bose fluid is of particular interest as even if full order is precluded, a residual "quasi-long" range order arises at low temperatures. 

In my talk, I will present an experimental study of the emergence of extended phase coherence in a weakly interacting atomic gas confined in a novel quasi-2D geometry, with a flat in-plane trap bottom. We will in particular explore the dimensional crossover of Bose Einstein Condensation. We will characterize the onset  of phase coherence as a steady state property of the gas  using both velocity distribution measurements and matter-wave interferometry. These measurements evidence in a subtle way the transverse condensation phenomenon, in which a significant fraction of atoms accumulates in the ground state of the motion perpendicular to the atom plane. We will also investigate the dynamical aspects of the transition through the detection of topological defects nucleated in a quench cooling of the gas, and we will compare our results to the predictions of the Kibble--Zurek theory for the conventional BEC second-order phase transition.
LOCATION:Erwin Schrödinger Saal
DTSTART:20141016T090000
DTEND:20141016T100000
TZID: Europe/Vienna
END:VEVENT
END:VCALENDAR