Nonequilibrium coherence dynamics of a soft boson lattice

Abstract

We study the nonequilibrium evolution of the phase coherence of a Bose-Einstein condensate in a one-dimensional optical lattice as the lattice array is suddenly quenched from a highly-number-squeezed to a superfluid state. We observe slowly damped phase coherence oscillations in the regime of large filling factor ($\ensuremath{\sim}100$ bosons per site) at a frequency proportional to the generalized Josephson frequency.