Entanglement Dynamics of Quantum Oscillators Nonlinearly Coupled to Thermal Environments

TL;DR

This paper investigates how two quantum harmonic oscillators maintain entanglement over time when nonlinearly coupled to thermal environments, revealing enhanced robustness due to parity conservation and differences from linear damping cases.

Contribution

It provides analytical and numerical analysis of entanglement dynamics in nonlinearly damped oscillators, highlighting the effects of bath configuration and nonlinear coupling on entanglement robustness.

Findings

Asymptotic entanglement is more robust with nonlinear coupling.

Parity conservation enhances entanglement stability.

Bath configuration effects are diminished in nonlinear damping.

Abstract

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-Redfield 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 find 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 configurations 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 configuration at low temperatures.