Characterization of stimulated excitations in a driven Bose-Einstein condensate

We apply the time-dependent Hartree-Fock-Bogoliubov (td-HFB) theory to describe the stimulated excitation driven by periodically modulating the interactions in a Bose-Einstein condensate (BEC). A comparison with the results calculated from the typical Bogoliubov approximation indicates that the additional interaction terms contributed by the excited modes play an important role to explain the dynamics of the stimulating process. The td-HFB model has not only painted a clear picture of the density wave propagation, but also partly explained the generation of the second order harmonic of the excited modes. The theoretical framework can be directly employed to study similar driven processes.