Nonclassical correlations provide a resource for many applications in quantum technology as well as providing strong evidence that a system is indeed operating in the quantum regime. Optomechanical systems can be arranged to generate quantum entanglement between the mechanics and a mode of travelling light. Here we propose automated optimisation of the production of quantum correlations in such a system, beyond what can be achieved through analytical methods, by applying Bayesian optimisation to the control parameters. Two-mode optomechanical squeezing experiment is simulated using a detailed theoretical model of the system, while the Bayesian optimisation process modifies the controllable parameters in order to maximise the non-classical two-mode squeezing and its detection, independently of the inner workings of the model. The Bayesian optimisation treats the simulations or the experiments as a black box. This we refer to as \emph{theory-blind} optimisation, and the optimisation process is designed to be unaware of whether it is working with a simulation or the actual experimental setup. We find that in the experimentally relevant thermal regimes, the ability to vary and optimise a broad array of control parameters provides access to large values of two-mode squeezing that would otherwise be difficult or intractable to discover. In particular we observe that modulation of the driving frequency around the resonant sideband, when added to the set of control parameters, produces strong nonclassical correlations greater on average than the maximum achieved by optimising over the remaining parameters. We also find that using our optimisation approach raises the upper limit to the thermal regime in which squeezing can be achieved. This extends the range of experimental setups in which non-classical correlations could be generated beyond the region of high quantum cooperativity.
Nonclassical correlations provide a resource for many applications in quantum technology as well as providing strong evidence that a system is indeed operating in the quantum regime. Optomechanical systems can be arranged to generate quantum entanglement between the mechanics and a mode of travelling light. Here we propose automated optimisation of the production of quantum correlations in such a system, beyond what can be achieved through analytical methods, by applying Bayesian optimisation to the control parameters. Two-mode optomechanical squeezing experiment is simulated using a detailed theoretical model of the system, while the Bayesian optimisation process modifies the controllable parameters in order to maximise the non-classical two-mode squeezing and its detection, independently of the inner workings of the model. The Bayesian optimisation treats the simulations or the experiments as a black box. This we refer to as \emph{theory-blind} optimisation, and the optimisation process is designed to be unaware of whether it is working with a simulation or the actual experimental setup. We find that in the experimentally relevant thermal regimes, the ability to vary and optimise a broad array of control parameters provides access to large values of two-mode squeezing that would otherwise be difficult or intractable to discover. In particular we observe that modulation of the driving frequency around the resonant sideband, when added to the set of control parameters, produces strong nonclassical correlations greater on average than the maximum achieved by optimising over the remaining parameters. We also find that using our optimisation approach raises the upper limit to the thermal regime in which squeezing can be achieved. This extends the range of experimental setups in which non-classical correlations could be generated beyond the region of high quantum cooperativity.
Abstract Nonclassical correlations provide a resource for many applications in quantum technology as well as providing strong evidence that a system is indeed operating in the quantum regime. Optomechanical systems can be arranged to generate nonclassical correlations (such as quantum entanglement) between the mechanical mode and a mode of travelling light. Here we propose automated optimization of the production of quantum correlations in such a system, beyond what can be achieved through analytical methods, by applying Bayesian optimization to the control parameters. A two-mode optomechanical squeezing experiment is simulated using a detailed theoretical model of the system and the measurable outputs fed to the Bayesian optimization process. This then modifies the controllable parameters in order to maximize the non-classical two-mode squeezing and its detection, independently of the inner workings of the model. We focus on a levitated nano-sphere system, but the techniques described are broadly applicable in optomechanical experiments, and also more widely, especially where no detailed theoretical treatment is available. We find that in the experimentally relevant thermal regimes, the ability to vary and optimize a broad array of control parameters provides access to large values of two-mode squeezing that would otherwise be difficult or intractable to discover via analytical or trial and error methods. In particular we observe that modulation of the driving frequency around the resonant sideband allows for stronger nonclassical correlations. We also observe that our optimization approach finds parameters that allow significant squeezing in the high temperature regime. This extends the range of experimental setups in which non-classical correlations could be generated beyond the region of high quantum cooperativity.
Quantum optomechanical systems enable versatile control of non-classical light. We study two-mode squeezed-light generation in a driven optomechanical cavity with parametrically amplified optical modes coupled to mechanical resonator. Coherent driving reveals a rich control landscape where parametric nonlinearity, optomechanical coupling, and reservoir interactions jointly tailor quantum correlations-including two-mode squeezing, entanglement, steering, and discord. Remarkably, mechanical oscillators not only mediate optical entanglement but also act as a squeezing resource, enabling enhancement or suppression of quantum correlations via parameter tuning. We derive steady-state second-order moments and closed-form covariance matrix expressions, quantifying entanglement via logarithmic negativity, steering via Reid criterion, and discord via von Neumann entropy, providing a comprehensive framework for optimized generation of quantum correlations in hybrid quantum systems.
Stationary entanglement between the motion of macroscopic objects and light is a long-standing goal of quantum optomechanics, with implications for both fundamental tests of quantum physics and emerging quantum technologies. We report the generation of quantum entanglement between the center-of-mass motion of a nanosphere levitated in an optical tweezer inside an optical cavity and the electromagnetic field. By heterodyne detection, we reconstruct the full set of optomechanical correlations and observe a violation of separability bounds between the mechanical motion and the quadratures of a propagating optical mode. This demonstrates the distribution of nonclassical correlations beyond the interaction region. The entanglement is generated at room temperature and remains robust over a broad range of parameters. Our results establish levitated optomechanical systems as a promising platform for continuous-variable quantum communication and for tests of macroscopic quantum physics.
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.
This work investigates the emergence of Non-classical Features in a pump-free hybrid atom-optomechanical system, addressing key limitations of conventional platforms that rely on strong coherent driving and are highly vulnerable to thermal decoherence. We propose a novel architecture in which a squeezed vacuum reservoir acts as a pre-correlated quantum environment, enabling the deterministic generation and stabilization of nonclassical correlations without the need for an external laser pump. By exploiting reservoir-engineered interactions, the system supports robust quadrature squeezing and multipartite entanglement across a wide range of operational parameters. Our analysis demonstrates that the hybrid system achieves significant squeezing levels approaching 90%, while simultaneously satisfying the DGCZ inseparability criterion, confirming the presence of strong continuous-variable entanglement. Importantly, these nonclassical signatures remain resilient under extreme thermal conditions, withstanding thermal occupancies as high as (nth = 1500), which substantially exceeds the tolerance of traditional laser-driven optomechanical systems. The underlying mechanism is attributed to passive correlation injection from the engineered reservoir, which effectively suppresses thermal noise and enhances quantum coherence even in weak-coupling and low-power regimes. This eliminates the need for active pumping, thereby reducing energy consumption and experimental complexity. Furthermore, the hybrid atom-optomechanical configuration introduces additional tunability through atomic gain and population inversion, thereby allowing flexible control over system dynamics and correlation properties. Overall, the proposed scheme establishes a scalable and energy-efficient pathway toward realizing robust quantum correlations in realistic noisy environments. It opens new prospects for cryogen-free quantum technologies, including quantum-enhanced sensing, precision metrology, and long-distance entanglement distribution.
In an optomechanical system consisting of two Fabry–Pérot cavities fed by squeezed light and coupled via Coulomb interaction, we respectively use the logarithmic negativity, Gaussian discord and Gaussian coherence to analyze the behavior of three different indicators of nonclassicality, namely the entanglement, quantum discord and quantum coherence. We perform the rotating wave approximation and work in the resolved sideband regime. In two bi-mode states (optical and mechanical), the coherence is generally found to be greater than entanglement and discord. More interestingly, we show that the Coulomb interaction can be used either to degrade or enhance the nonclassical properties of the optical subsystem. In addition, compared with the discord and coherence, the mechanical entanglement is found strongly sensitive to both thermal and Coulomb effects, and it requires a minimum value of cooperativity to be generated. Remarkably, this minimum increases when increasing the Coulomb coupling strength. Finally, we notice that an optimal transfer of quantum correlations between the optical and mechanical subsystems is achieved in the absence of the Coulomb interaction.