Entanglement dynamics of quantum oscillators nonlinearly coupled to thermal environments

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.

Dynamics of two levitated nanospheres nonlinearly coupling with non-Markovian environment*

“…The dynamics of a nanoparticle that nonlinearly couples to its reservoir has been theoretically studied in the Markovian regime. [18,19] Non-Markovian theory plays an important role in treating a realistic system. The non-Markovian environment usually can keep the coherence and suppress the dissipation.…”

Exact decoherence-free state of two distant quantum systems in a non-Markovian environment

“…It was found that the decoherence caused by a common environment can play a constructive role in generating stable entanglement between two quantum systems [9][10][11][12]. The intrinsic physics is the existence of the decoherence-free state (DFS) [13][14][15], which triggers the enthusiasm of relearning the role of decoherence of composite system caused by a common environment from different systems such as harmonic oscillators [16][17][18][19][20] and spins [21][22][23][24], and different environments such as crystal chains [25][26][27] and waveguides [23,24,[28][29][30][31].…”