Phase-Reference Control of Steady-State Entanglement in Open Quantum Systems

TL;DR

This paper demonstrates how the phase reference of a phase-sensitive reservoir controls steady-state entanglement in open quantum systems, enabling reservoir engineering to generate and optimize entanglement.

Contribution

It introduces a covariance-matrix approach showing local phase-sensitive dissipation combined with coherent coupling can produce and regulate steady-state entanglement.

Findings

Finite entangled region with optimal squeezing strength.

Coherent coupling regulates conversion of local squeezing into nonlocal correlations.

Different steady states arise depending on the reservoir phase reference.

Abstract

We show that steady-state entanglement in open quantum systems is controlled by the phase reference of a phase-sensitive reservoir. Using a covariance-matrix approach for Gaussian-preserving dynamics, we demonstrate that purely local, phase-sensitive dissipation can generate entanglement when combined with coherent coupling. The steady state exhibits a finite entangled region with an optimal squeezing strength that maximizes both the magnitude and thermal robustness of entanglement. We find that coherent coupling does not enhance entanglement monotonically, but instead regulates the conversion of local squeezing into nonlocal correlations. Importantly, the coupling dependence is controlled by the phase reference of the squeezed reservoir: phase-locked (rotating-frame) and laboratory-frame implementations yield qualitatively distinct steady states and entanglement structure. These results establish phase-sensitive reservoir engineering as a controllable route to steady-state entanglement in continuous-variable systems. Steady-state entanglement in phase-sensitive open systems depends explicitly on the reservoir phase reference and is not invariant under changes of that reference.}