318 research outputs found
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
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
Dymamical Casimir emission from polariton condensates
We study theoretically the dynamical Casimir effect in an exciton-polariton
condensate that is suddenly created by an ultrashort laser pulse at normal
incidence. As a consequence of the abrupt change of the quantum vacuum,
Bogoliubov excitations are generated. The subsequent evolution, governed by
polariton interactions and losses, is studied within a linearized truncted
Wigner approximation. We focus in particular on the momentum distribution and
spatial coherence. The limiting behavior at large and small momenta is
determined analytically. A simple scaling relation for the final condensate
depletion as a function of the system parameters is found and the correlation
length is shown to depend linearly on the condensate depletion.Comment: 5 pages, 4 figure
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