Dynamical quantum depletion in polariton condensates

We present a theoretical study of the quantum depletion of microcavity polaritons that are excited with a resonant laser pulse. The dynamics of the quantum fluctuations are interpreted in the context of quantum quenches in general and in terms of the dynamical Casimir effect in particular. We compute the time evolution of the first and second order correlation functions of the polariton condensate. Our theoretical modelling is based on the truncated Wigner approximation for interacting Bose gases. For homogeneous systems, analytical results are obtained in the linearised Bogoliubov approximation. Inhomogeneous systems are studied numerically by Monte Carlo simulations.Comment: 7 pages, 10 figure

Optically bistable driven-dissipative Bose-Hubbard dimer: Gutzwiller approaches and entanglement

We theoretically examine the driven-dissipative Bose-Hubbard dimer in the optical bistable regime. Various approximation schemes based on a Gutzwiller mean field decoupling are applied and compared. Depending on the system parameters we show that a decoupling with respect to the real space or to the reciprocal space can be more accurate. The Gutzwiller decoupling is applied both at the level of the density matrix and for the wavefunction during a quantum trajectory simulation. The latter is shown to be a more accurate approximation. A Gaussian approximation for the non-homogeneous anti-bonding mode is also explored. We also show that entanglement in this system is witnessed by squeezing in reciprocal space