Quench Dynamics and Long-Range Coherence in Quasi-One-Dimensional Attractive Bose Gases*

Attractive Bose gases in low dimensions offer versatile platforms for studying non-equilibrium quench dynamics. Ultracold gases quenched to attractive interactions are known to spontaneously form bright solitons in one and two dimensions due to modulational instability. Furthermore, in one-dimensional (1D) systems, integrability leads to fascinating dynamics, including transient breathing behavior in long-range density and phase correlations distinct from phase-independent solitons. However, the manifestation of these effects in quasi-1D gases with extended dimensionality and realistic three-body losses remains elusive. In this talk, I will discuss our experimental investigation of quench dynamics and long-range coherence in quasi-1D Bose gases confined in an optical box. The gases are quenched from repulsive to attractive interactions, emitting shockwaves from an effective edge-induced dam break. Using in-situ density and matter-wave interference imaging, we observe a novel interplay with modulational instability seeded from initial density fluctuations in the bulk, featuring dynamical, phase-coherent spatial modulations. At sufficiently long times after long-range correlations become suppressed, we find that quasi-long-range order can be re-established following a quench back to the repulsive regime, accompanied by defect generation reminiscent of the celebrated Kibble-Zurek mechanism across a continuous phase transition. Our study provides a promising route to explore quantum quench dynamics of attractive Bose gases in low dimensions.