Entanglement Dynamics of Quantum Oscillators Nonlinearly Coupled to Thermal Environments
We study the asymptotic entanglement of two quantum harmonic oscillators nonlinearly coupled
to an environment. Coupling to independent baths and a common bath are investigated. Numerical
results obtained using the Wangsness-Bloch-Redeld method are supplemented by analytical results
in the rotating wave approximation. The asymptotic negativity as function of temperature, initial
squeezing and coupling strength, is compared to results for systems with linear system-reservoir coupling.
We nd that due to the parity conserving nature of the coupling, the asymptotic entanglement
is considerably more robust than for the linearly damped cases. In contrast to linearly damped systems,
the asymptotic behavior of entanglement is similar for the two bath congurations in the
nonlinearly damped case. This is due to the two-phonon system-bath exchange causing a supression
of information exchange between the oscillators via the bath in the common bath conguration at low temperatures.
Nonlinear quantum dynamics