Observation of dynamical instability for a Bose-Einstein condensate in a moving 1D optical lattice

TL;DR

This paper experimentally investigates the dynamical instability of a Bose-Einstein condensate in a moving 1D optical lattice, revealing how instability onset affects condensate lifetime and density structures, aligning with Gross-Pitaevskii theory.

Contribution

It provides the first experimental observation of dynamical instability effects in a BEC within a moving optical lattice, confirming theoretical predictions.

Findings

Condensate lifetime depends strongly on quasimomentum.

Dynamical instability causes rapid density structure formation.

Results agree with Gross-Pitaevskii theory predictions.

Abstract

We have experimentally studied the unstable dynamics of a harmonically trapped Bose-Einstein condensate loaded into a 1D moving optical lattice. The lifetime of the condensate in such a potential exhibits a dramatic dependence on the quasimomentum state. This is unambiguously attributed to the onset of dynamical instability, after a comparison with the predictions of the Gross-Pitaevskii theory. Deeply in the unstable region we observe the rapid appearance of complex structures in the atomic density profile, as a consequence of the condensate phase uniformity breakdown.