Non-equilibrium dynamics of attractive Bose gases in an optical box*

Atomic quantum gases confined in a box potential offer a versatile platform for studying non-equilibrium dynamics induced by interaction effects, vorticity, as well as effects of the box or an addressing potential. In this poster, we present our investigations of different quench-induced dynamics under two scenarios: multi-mode breathing dynamics in a quasi-one-dimensional (1D) Bose gas under attractive interactions, as well as collapse to a “vortex soliton” state in a rotating 2D gas. In the first case, we prepare a quasi-1D gas, and monitor evolutions of both local density and phase fluctuations after a quench from repulsive to attractive interaction. We observe recurring gain and loss of phase coherence, and periodic density modulation, resulting from the nonlinear stage of modulational instability. In the second case, we create a quantum vortex in a homogeneous 2D superfluid and observe that for a certain interaction strength, a 2D gas can evolve into a self-trapped state with a donut-shaped profile during a 2D time-of-flight (TOF), forming a vortex soliton carrying one unit of angular momentum. We also study the eventual fragmentation of such a rotating gas at different interactions into disjoint density blobs, which resembles a necklace of bright solitons. This azimuthal instability is quantified by extracting the density power spectrum in different azimuthal modes.