Dynamical instability of a dark soliton in a quasi-one-dimensional Bose-Einstein condensate perturbed by an optical lattice

Abstract

The motion of a dark soliton is investigated in a one-dimensional dilute Bose-Einstein condensate confined in a harmonic trap and an optical lattice. The harmonic trap induces a dynamical instability of the soliton, culminating in sound emission. The presence of the perturbing optical lattice enhances the instability, and in addition, dephases the emitted sound waves, thus preventing stabilization of the soliton by sound reabsorption. This instability can be probed experimentally by monitoring the soliton oscillations under various lattice configurations, which can be realized by changing the intensity and angle between the laser beams that form the lattice. For short enough times, such that..