Long-time nonlinear dynamical evolution for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>P</mml:mi></mml:math>-band ultracold atoms in an optical lattice

Abstract

We report the long-time nonlinear dynamical evolution of ultracold atomic gases in the $P$ band of an optical lattice. A Bose-Einstein condensate is fast and efficiently loaded into the $P$ band at zero quasimomentum with a nonadiabatic shortcut method. For the first 1.5 ms, this momentum state undergoes oscillations due to coherent superposition of different bands, which are followed by oscillations up to 60 ms of a much longer period. Our analysis shows the dephasing from the nonlinear interaction is very conducive to the long-period oscillations induced by the variable force due to the harmonic confinement.