# Enhanced entanglement of two optical modes in optomechanical systems via an optical parametric amplifier

## TL;DR

This paper explores how inserting an optical parametric amplifier into an optomechanical cavity enhances the steady-state entanglement between two optical modes, especially at cryogenic temperatures, by inducing single-mode squeezing.

## Contribution

It demonstrates that an optimal nonlinear gain of the OPA maximizes entanglement, providing a novel method to improve quantum correlations in optomechanical systems.

## Key findings

- Optimal OPA gain depends on system temperature.
- Significant entanglement enhancement at cryogenic temperatures.
- Single-mode squeezing improves two-mode entanglement.

## Abstract

We investigate the effect of a degenerate optical parametric amplifier (OPA) placed inside an optomechanical cavity on the steady-state entanglement of two cavity modes, which jointly interact with a mechanical resonator. Two cavity modes are respectively driven at the red and blue sideband associated with the mechanical resonator, which generates entanglement between them in the limit of resolved sideband. The OPA gives rise to single-mode squeezing of the cavity fields, which results in significant improvement of the two-mode entanglement. It is found that an optimal nonlinear gain of the OPA exists, depending on the system temperatures, which yields the maximum entanglement. The improvement is particularly remarkable for the system at cryogenic temperatures.

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Source: https://tomesphere.com/paper/1703.02666