Dephasing in coherently-split quasicondensates

TL;DR

This paper models the dephasing dynamics of coherently split one-dimensional quasicondensates, confirming subexponential coherence decay and analyzing the scaling of the dephasing time with density and temperature.

Contribution

It provides a numerical confirmation of the subexponential coherence decay law and details the dependence of dephasing time on physical parameters in a purely dephasing scenario.

Findings

Coherence decays as exp[-(t/t0)^{2/3}] over time.

Dephasing time t0 scales as the square of the ratio of density to temperature.

Full distribution function of interference contrast analyzed.

Abstract

We numerically model the evolution of a pair of coherently split quasicondensates. A truly one-dimensional case is assumed, so that the loss of the (initially high) coherence between the two quasicondensates is due to dephasing only, but not due to the violation of integrability and subsequent thermalization (which are excluded from the present model). We confirm the subexponential time evolution of the coherence between two quasicondensates $\propto \exp [-(t/t_0)^{2/3}]$, experimentally observed by S. Hofferberth {\em et. al.}, Nature {\bf 449}, 324 (2007). The characteristic time $t_0$ is found to scale as the square of the ratio of the linear density of a quasicondensate to its temperature, and we analyze the full distribution function of the interference contrast and the decay of the phase correlation.