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Journal of the Optical Society of America B

Generation of stationary entanglement and quantum discord in an optomechanical system through three-level atoms

Abraham Abebe Kibret, Tewodros Yirgashewa Darge, Tesfay Gebremariam Tesfahannes

Published Apr 16, 2024• 9 citations
Publisher

Abstract

In this paper, we investigate the stationary entanglement and quantum discord between the cavity and mechanical oscillator mode of an optomechanical system whose cavity contains three-level atoms. We examine how sharing entanglement and correlations would be affected by increasing the level of atoms injected into the cavity. In particular, using the appropriate preference of injected atoms to the cavity and optical cavity detuning, we found the impact of atoms and couplings on the degree of steady-state entanglement and quantum discord. Consequently, the stationary entanglement and quantum discord together rise to a certain range of normalized detuning and atom injection levels. Furthermore, both entanglement and Gaussian quantum discord are enhanced when three-level atoms are present, and the maximum entanglement manifests closest to the ringing case. Moreover, we are aware that the system’s physical parameters affect the generation of stationary entanglement and quantum correlation. Therefore, these results may provide a platform for a valuable asset in the practical realization of continuous variable entanglement and quantum information processing.

DOI
10.1364/josab.516660

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In this paper, we investigate the stationary entanglement and quantum discord between the cavity and mechanical oscillator mode of an optomechanical system whose cavity contains three-level atoms. We examine how sharing entanglement and correlations would be affected by increasing the level of atoms injected into the cavity. In particular, using the appropriate preference of injected atoms to the cavity and optical cavity detuning, we found the impact of atoms and couplings on the degree of steady-state entanglement and quantum discord. Consequently, the stationary entanglement and quantum discord together rise to a certain range of normalized detuning and atom injection levels. Furthermore, both entanglement and Gaussian quantum discord are enhanced when three-level atoms are present, and the maximum entanglement manifests closest to the ringing case. Moreover, we are aware that the system’s physical parameters affect the generation of stationary entanglement and quantum correlation. Therefore, these results may provide a platform for a valuable asset in the practical realization of continuous variable entanglement and quantum information processing.
Quantum discord, and related indicators, are raising a relentless interest as a novel paradigm of nonclassical correlations beyond entanglement. Here, we discover a discord-activated mechanism yielding steady-state entanglement production in a realistic continuous-variable setup. This comprises two coupled optomechanical cavities, where the optical modes (OMs) communicate through a fiber. We first use a simplified model to highlight the creation of steady-state discord between the OMs. We show next that such discord improves the level of stationary optomechanical entanglement attainable in the system, making it more robust against temperature and thermal noise.
In this paper, we investigate the dynamics of quantum correlations for the continuous-variable bipartite optomechanical system in the presence of homodyne mediated quantum feedback. The system is constructed using the Fabry–Perot cavity and a mechanical oscillator. In detail, we have studied the quantum entanglement via logarithmic negativity, quantum discord, and quantum steering between the optical and mechanical modes. The results show that the maximum entanglement between the optical and mechanical modes occurred out of the resonance frequency at the steady-state region due to the presence of the optical feedback. We also employ quantum steering to see the steerability between the modes. It is observed that the quantum entanglement increases when the effective detuning frequency increases, however, the quantum discord and steering decrease when the effective detuning frequency increases for a given quantum feedback strength with other parameters of the system are to be fixed. Moreover, the presence of quantum feedback has an enhancement effect on the quantum correlations.
In this paper, we analyze, under realistic experimental conditions, entanglement and quantum discord in a two-mode Gaussian state [Formula: see text] coupled to a thermal reservoir. The mode [Formula: see text]([Formula: see text]) is generated during the first(second) transition of a nondegenerate three-level laser. The gain medium of the laser is a set of three-level atoms in a cascade configuration. The atoms are prepared initially in a superposition of the upper and lower levels. In the good cavity-limit, applying the master equation we obtain the covariance matrix of the state [Formula: see text] at steady-state. We use the entanglement of formation and the Gaussian quantum discord to quantify entanglement and quantum correlations beyond entanglement, respectively. The two indicators of nonclassicality are defined by means of the von Neumann entropy, and obtained as functions of the parameters characterizing the physical and environmental parameters of the state [Formula: see text], i.e. atomic coherence, dissipation and thermal photon number. As results, we find that maximum entanglement and discord could be achieved by adjusting the degree of atomic coherence. In contrary to the expectation based on the assumption that entanglement is a part of quantum discord, it is found that the latter can be less than the former. Under thermal noise effect, we find that quantum discord measured when the state [Formula: see text] exhibits entanglement diminishes drastically, while that measured when the [Formula: see text] is separable displays a relatively robust behavior seeming to be captured over a wide range of temperature. Our results assert that nondegenerate three-level lasers may play a crucial role in the implementation of quantum processing tasks, particularly those who do not need entangled states.
We present a proposal to generate quintupartite entanglement with an optomechanical dual-cavity containing an ensemble of Λ-type three-level atoms. By solving the Heisenberg-Langevin equations, we show that entanglement among the two cavity fields, two mechanical oscillators, and atoms can be realized via atomic coherence and cavity field radiation pressure. In addition, within the experimentally available range of parameters, the larger the input laser power, atomic ensemble number, and quality factors of the cavity and mechanical oscillators, and the smaller the environmental temperature, the stronger the multipartite entanglement. This atom-cavity-optomechanical hybrid system provides an efficient and convenient platform for quantum states exchange between macroscopic (mechanical oscillators) and microscopic (atoms, photons) matters, and may find promising applications in realistic quantum information processing.
Abstract We theoretically investigate quantum entanglement and coherence in a hybrid Laguerre–Gaussian rotating cavity optomechanical system with two-level atoms, where cavity and mechanical modes are coupled through the exchange of orbital angular momentum. Our study shows that the injection of atoms with a suitable choice of the physical parameters can significantly improve the degree of optomechanical entanglement in all aspects. In the study of quantum coherence research, we show more comprehensively the negative and positive effects of atoms on the coherence. The result obtained is that only when the atom is significantly off-resonant to driving field, the coupling strength in between the atoms and light field increases and the quantum coherence can be enhanced, otherwise it will reduce quantum coherence. In addition, the atomic decay suppresses quantum coherence phenomenon.
We investigate the correlation of mechanical systems of nondegenerate three-level laser with parametric oscillator in optomechanical cavity coupled to a two-mode squeezed vacuum reservoir. The quantum properties of the mechanical systems as a result of the correlation have been analyzed using the expectation values of mechanical mode variables at steady state and the eigenvalues of the reduced covariance matrix of the two sub-mechanical systems. The logarithmic negativity, steerability, and quantum discord criterion for entanglement, steerability, and quantum discord, respectively confirm that bipartite sub-mechanical systems are correlated. The results show that the bipartite sub-mechanical systems exhibit entanglement two-way steering and non-classical correlation or quantum discord. Moreover, the sub-mechanical system exhibits squeezing in the minus quadrature or momentum. The correlation properties of sub-mechanical systems are depend on the reservoir but the cavity laser has no effect on the quantum correlation of the sub-mechanical systems.