Adiabaticity when raising a uniform three-dimensional optical lattice in a bimodal Bose-Einstein condensate

Abstract

Using the time-dependent Bogoliubov approach, we study adiabaticity for a two-component Bose-Einstein condensate in a three-dimensional time-dependent optical lattice with unit filling, in the superfluid and weakly interacting regime. We show that raising the lattice potential height can couple the ground state of the Bogoliubov Hamiltonian to excited states with two quasiparticles of opposite quasimomenta. In the symmetric case for interactions and density in the two components these represent sound waves where the two components oscillate out of phase. We find an analytic expression for the adiabatic time, its dependence on the fraction of atoms in each component, and its scaling with the system size.