In this study, we control the quantum correlations existing between a movable mirror and atoms in hybrid atom-optomechanical system using rotating wave approximation (RWA) in adiabatic regime. We use the Mancini criterion to measure the entanglement, the purity to quantify the degree of mixedness and the Gaussian geometric discord (GGD) to characterize the quantum correlations even beyond entanglement. We study the effect of the optomechanical cooling rate and the cooperativity atomic on the transfer of quantum correlations between the movable mirror and atoms under the thermal effect. We also investigate the robustness of the GGD with respect to entanglement by exploiting recent experimental parameters.
In this study, we control the quantum correlations existing between a movable mirror and atoms in hybrid atom-optomechanical system using rotating wave approximation (RWA) in adiabatic regime. We use the Mancini criterion to measure the entanglement, the purity to quantify the degree of mixedness and the Gaussian geometric discord (GGD) to characterize the quantum correlations even beyond entanglement. We study the effect of the optomechanical cooling rate and the cooperativity atomic on the transfer of quantum correlations between the movable mirror and atoms under the thermal effect. We also investigate the robustness of the GGD with respect to entanglement by exploiting recent experimental parameters.
We investigate the generation of quantum correlations between mechanical modes and optical modes in an optomechanical system, using the rotating wave approximation. The system is composed of two Fabry–Pérot cavities separated in space; each of the two cavities has a movable end-mirror. Our aim is the evaluation of entanglement between mechanical modes and optical modes, generated by correlations transfer from the squeezed light to the system, using Gaussian intrinsic entanglement as a witness of entanglement in continuous variables Gaussian states, and the quantification of the degree of mixedness of the Gaussian states using the purity. Then, we quantify nonclassical correlations between mechanical modes and optical modes even beyond entanglement by considering Gaussian geometric discord via the Hellinger distance. Indeed, entanglement, mixdness, and quantum discord are analyzed as a function of the parameters characterizing the system (thermal bath temperature, squeezing parameter, and optomechanical cooperativity). We find that, under thermal effect, when entanglement vanishes, purity and quantum discord remain nonzero. Remarkably, the Gaussian Hellinger discord is more robust than entanglement. The effects of the other parameters are discussed in detail.
We study the dynamics of classical-quantum correlations in the nonadiabatic regime, using the rotating wave approximation (RWA), between two movable mirrors of two spatially separated Fabry–Pérot cavities, each of the two cavities having a movable end-mirror and coupled to a two-mode squeezed light from spontaneous parametric down-conversion. This work completes our previous work [M. Amazioug, M. Nassik and N. Habiballah, Eur. Phys. J. D 72, 171 (2018)] where we have studied the transfer of quantum correlations in steady state. The Bures distance is used to quantify the amount of entanglement of the symmetrical squeezed thermal state, and the Gaussian quantum discord is considered to quantify the quantumness of the quantum correlations even though the two movable mirrors are separable. Furthermore, total correlations are quantified using quantum mutual information. Indeed, these three indicators depend mainly on the temperature of the movable mirror and the squeezing parameter in strong coupling regime.
In this paper, we analyze nonclassical correlations between bipartite states in two optomechanical systems. The first system (Sec. 2) consists of two nanoresonators spatially separated by broadband squeezed light, where each cavity has a fixed mirror and a movable one. The second system (Sec. 3) is an atom-optomechanical system consisting of an atomic ensemble placed inside an optical nanoresonator with a vibrating mirror. For both optomechanical systems, we give the Hamiltonian and the explicit expression of covariance matrix leading to the quantum equations describing the dynamic evolution of the system. Then, the nonclassical correlations are quantified using the logarithmic negativity and Gaussian quantum discord. We propose also a scheme for examining the evolution of Gaussian quantum steering and its asymmetry in each system. We show that the entanglement of the two mechanical modes is very strongly related to the parameters characterizing the environment where the movable mirrors evolve, in particular the squeeze parameter, the optomechanical cooperativity and thermal bath temperature.
The aim of this paper is to quantify the quantum correlations between mechanical and optical modes in an optomechanical system with two spatially separated Fabry–Pérot cavities. We use logarithmic negativity [Formula: see text] and entanglement of formation (EoF), respectively, to quantify entanglement between optical and mechanical modes, while Gaussian geometric discord (GGD) is used to capture all nonclassical correlations, including entanglement. These quantifiers are evaluated as functions of the physical parameters characterizing the environment and the system (the thermal bath temperature [Formula: see text], the photons number [Formula: see text], the optomechanical cooperativity [Formula: see text], the squeeze parameter [Formula: see text] and the drive pump power [Formula: see text]). By considering recent experimental parameters, we show that GGD is more robust than entanglement for high thermal bath temperature and low optomechanical cooperativity. We also find that these quantifiers improve with increasing optomechanical cooperativity. The effects of the other parameters are also discussed in detail.
We propose a scheme for entangling a movable mirror and two atomic ensembles in a coupled hybrid optomechanical system. Using the logarithmic negativity for the entanglement measure, we analyze the effect of the coupling strength between the two cavities on the entanglement of the movable mirror and the atomic ensembles, and we analyze the effect of the atom-cavity coupling constant on the entanglement of the movable mirror and the atomic ensembles. It is found that the entanglements of the movable mirror with one atomic ensemble transfer to the movable mirror with another atomic ensemble, and the robustness of the entanglement is enhanced by the coupling between the two cavities. The entanglements between the movable mirror and atomic ensembles are enhanced together with atom-cavity coupling increasing, and the entanglements have maxima in the accessibly parameters regime of the atom-cavity coupling constant.
Using the Gaussian Rényi-2 entropy, we analyse the behaviour of two different aspects of quantum correlations (entanglement and quantum discord) in two optomechanical subsystems (optical and mechanical). We work in the resolved sideband and weak coupling regimes. In experimentally accessible parameters, we show that it is possible to create entanglement and quantum discord in the considered subsystems by quantum fluctuations transfer from either light to light or light to matter. We find that both mechanical and optical entanglement are strongly sensitive to thermal noises. In particular, we find that the mechanical one is more affected by thermal effects than that optical. Finally, we reveal that under thermal noises, the discord associated with the entangled state decays aggressively, whereas the discord of the separable state (quantumness of correlations) exhibits a freezing behaviour, seeming to be captured over a wide range of temperature.