Particle creation in the spin modes of a dynamically oscillating two-component Bose-Einstein condensate

We investigate the parametric amplification of the zero-point fluctuations in the spin modes of a two-component Bose-Einstein condensate, triggered by the dynamical evolution of the condensate density. We first make use of a Thomas-Fermi approximation to develop a tractable theoretical model of the quantum dynamics of the Bogoliubov excitations in a harmonically trapped condensate with a time-dependent trapping frequency. The predictions of this model are then compared to an ab initio numerical study of the correlation functions of density and spin fluctuations for general spatially inhomogeneous configurations. Results are shown for the two cases of expanding and oscillating condensates: while the quantum excitation of spin modes remains weak and relatively featureless in the case of an expanding condensate, clear and experimentally promising signatures of particle creation are anticipated for the oscillating case under suitable resonance conditions between the density and the spin modes.

Automated summary

The research investigates the parametric amplification of zero-point fluctuations in the spin modes of a two-component Bose-Einstein condensate. Predictions show that quantum excitations of spin modes are weak and featureless in the case of expanding condensates, while clear and promising signs of particle creation are expected in oscillating condensates under suitable resonance conditions.