Measure and control of quantum correlations in optomechanics

Abstract

In this work, we analyze the enhancement of the transfer of the quantum correlations from squeezed light to movable mirrors in an optomechanical system. This transfer is produced using a degenerate parametric amplifier placed inside each of the two cavities of the system. These cavities are coupled via photon-hopping process. The double-cavity optomechanical system is pumped by squeezed light and driven by coherent laser sources. The two cavities are spatially coupled via a broadband squeezed light and driven at red-detuned sidebands. In our analysis, we shall work in the framework of the Markovian approximation. In each cavity, the optical mode is coupled to mechanical mode via radiation pressure. We discuss the quantum correlations (steering, entanglement and discord) of the two mechanical oscillators. We consider Gaussian quantum steering to measure the steerability between the two mechanical oscillators and the logarithmic negativity to measure quantum entanglement. The quantum correlations are measured even beyond entanglement via Gaussian quantum discord. We show that the logarithmic negativity depends on the parameter amplifier gain, the cavity–cavity coupling, the optomechanical cooperativity, the dissipation rate and the bath temperature of the mechanical oscillators. We found that the transfer of quantum correlations in the steady state can be enhanced via degenerate parametric amplifier for low dissipation rate and via strong coupling optomechanics. We show also that the quantum correlations are robust against thermal fluctuations. We discuss how this quantum discord is more robust than entanglement which is more robust than steering. By using recent experimental parameters, we show also that the proposed scheme can be implemented by current experimental technology.