Suppression of spontaneous defect formation in inhomogeneous Bose gases

Abstract

We investigate the defect suppression effect in an inhomogeneous trapped atomic Bose gas which is quenched into a superfluid phase. We find that the spontaneous defect production is relatively more suppressed in the sample's outer region with higher atomic density gradient. By measuring the spatial distribution of created defects for various quench times, we show that the power-law scaling of the local defect density with the quench time is enhanced in the outer region, which is consistent with the Kibble-Zurek mechanism including the causality effect due to the spatial inhomogeneity of the system. This work opens an avenue in the study of nonequilibrium phase transition dynamics using the defect position information.