Expansion of a one-dimensional Bose gas: the role of interactions and kinetic-energy driving

Abstract

We study the expansion of a one-dimensional boson gas by suddenly increasing the length of the chain where it resides. We consider three initial ground-state configurations: the Mott insulator, the conventional superfluid clumped around zero momentum, and the cat-like state with peaks at momenta $\pm \pi /2$, resulting from rapid kinetic driving. In turn, we consider three types of expansion: spectroscopic (with interactions tuned to zero), dynamic (with standard short-range repulsive interactions) and under kinetic driving. The numerical calculations are exact. We compute the momentum- and real-space one-particle densities as well as the two-particle momentum correlations. The spectroscopic time-of-flight experiment faithfully reflects the initial momentum distribution. For the dynamic expansion starting from an insulator, we reproduce the non-equilibrium quasi-condensation into momenta $\pm \pi /2$ while noticing correlations in the momentum distribution, and provide an intuitive physical picture. A discussion of various measures of the momentum correlations is also presented.

19 pages, 8 figures. Slightly revised in response to referee reports

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Cited by in corpus (1)

• Superfluidity from correlations in driven boson systems