Dynamical Casimir effect in ultra-cold matter with a time-dependent effective charge

We propose a new scheme for observing the phonon analogue of the dynamical Casimir effect (DCE) in a gas of laser-cooled atoms. Namely, the emission of phonon pairs from vacuum can happen due to periodic variations of the effective charge of atoms, caused by a small intensity modulation of laser beams used for cooling and trapping the atoms. Then the 'temporal Bragg diffraction' results in phonon backscattering in time, equivalent to the DCE. (paper)