Modulational instability of a two-dimensional Bose-Einstein condensate in an optical lattice through a variational approach

Abstract

We investigate the modulational instability of a two-dimensional Bose-Einstein condensate in a two-dimensional optical lattice using a time-dependent variational approach. Within this framework, we derive the ordinary differential equations for time evolution of the amplitude and phase of modulational perturbations. Analyzing these equations and the Hamiltonian of the system, we obtain the modulational instability criterion.