Matter Wave Jet Emission from a Driven Bose-Einstein Condensate
Zhigang Wu, Hui Zhai
Abstract
Emission of matter wave jets has been recently observed in a Bose-Einstein condensate confined by a cylindrical box potential, induced by a periodically modulated inter-particle interaction (Nature {\bf 551}, 356 (2017)). In this letter we apply the number-conserving time-dependent Bogoliubov theory to study the highly non-equilibrium quantum dynamics in this system. Without any fitting parameter, our theoretical calculations on the dynamics of the jet emission and the angular density correlation are in excellent quantitative agreement with the experimental measurements. In particular, our theory interprets the angular density correlation of the jets as the Hanbury-Brown-Twiss effect between the excited quasi-particles with different angular momenta, and this explains the puzzling observation of the asymmetric density correlations between the jets with the same and opposite momenta. We also analytically show that the number of atoms in the jet emission increases quadratically at early times and is followed by an exponential growth at later times.