We propose how to generate a tripartite light-vibration entanglement by controlling an optical dark mode (ODM), which is induced by the coupling of two optical modes to a common vibrational mode. This ODM is decoupled from the vibration, and it can be controlled on demand by employing a synthetic gauge field, which can enable efficient switching between the ODM-unbreaking and ODM-breaking regimes. We find that the tripartite optomechanical entanglement is largely suppressed in the ODM-unbreaking regime, but it is significantly enhanced in the ODM-breaking regime. In particular, the noise robustness of quantum entanglement in the ODM-breaking regime can be more than twice than that in the ODM-unbreaking regime. This study offers a method for protecting and enhancing fragile quantum resources and for constructing noise-tolerant and dark-mode-immune quantum processors and entangled networks.
We propose how to generate a tripartite light-vibration entanglement by controlling an optical dark mode (ODM), which is induced by the coupling of two optical modes to a common vibrational mode. This ODM is decoupled from the vibration, and it can be controlled on demand by employing a synthetic gauge field, which can enable efficient switching between the ODM-unbreaking and ODM-breaking regimes. We find that the tripartite optomechanical entanglement is largely suppressed in the ODM-unbreaking regime, but it is significantly enhanced in the ODM-breaking regime. In particular, the noise robustness of quantum entanglement in the ODM-breaking regime can be more than twice than that in the ODM-unbreaking regime. This study offers a method for protecting and enhancing fragile quantum resources and for constructing noise-tolerant and dark-mode-immune quantum processors and entangled networks.
Entanglement of light and multiple vibrations is a key resource for multichannel quantum information processing and memory. However, entanglement generation is generally suppressed, or even fully destroyed, by the dark-mode (DM) effect induced by the coupling of multiple degenerate or near-degenerate vibrational modes to a common optical mode. Here we propose how to generate optomechanical entanglement via DM breaking induced by synthetic magnetism. We find that at nonzero temperature, light and vibrations are separable in the DM-unbreaking regime but entangled in the DM-breaking regime. Remarkably, the threshold thermal phonon number for preserving entanglement in our simulations has been observed to be up to 3 orders of magnitude stronger than that in the DM-unbreaking regime. The application of the DM-breaking mechanism to optomechanical networks can make noise-tolerant entanglement networks feasible. These results are quite general and can initiate advances in quantum resources with immunity against both dark modes and thermal noise.
Quantum entanglement is an interesting resource for modern quantum technologies, where generating multiple quantum entanglement is highly required. However, entanglement engineering between multiple modes is strongly suppressed by dark mode effect. Here, we proposed a scheme based on molecular cavity optomechanical structure that enhances quantum bipartite and tripartite entanglement via dark mode breaking. Our proposal consists of an optical cavity that hosts two molecular ensembles which are coupled through an intermolecular coupling. A vibrational hopping rate Jm captures the intermolecular coupling that is phase modulated via the synthetic gauge field method. The breaking of the dark mode is controlled by tuning both the intermolecular coupling and its modulation phase. By adjusting these parameters in our proposal, we can flexibly switch between the Dark Mode Unbroken (DMU) and the Dark Mode Broken (DMB) regimes. We find that in the dark-mode-unbroken regime, the amount of the generated bipartite and tripartite entanglement is significantly low or is suppressed. In contrast, in the dark-mode-broken regime, the entanglement is greatly enhanced,i.e., up to twofold enhancement. Moreover, the generated entanglement is more resilient against thermal noise in the dark-mode-broken regime compared to the thermal robustness in the unbroken regime. Therefore, our proposed scheme serves as a benckmark system to improve quantum correlations engineering, and to generate noise-tolerant quantum resources for applications in numerous modern quantum technologies.
We propose a scheme to generate multi-paths entanglement in an optomechanical system by exploiting polarized electromagnetic fields and dark mode control. Our system consists of two mechanically coupled mechanical resonators, which are driven by a common electromagnetic field. An inclusion of a polarizer induces linear polarizations of the electromgnetic field corresponding to the vertical (transverse electric (TE) and horizontal (transverse magnetic [(TM]) modes, which drive the mechanical resonators. Without the mechanical coupling Jm=0, the polarization angle (φ) controls dark mode in the system. The breaking of this dark mode leads to multi-paths engineering of bipartite optomechanical entanglements. By switching on the phonon hopping rate (Jm=0), both the polarization angle and the modulation phase of the mechanical coupling allow a further control of the dark mode. The simultaneous Dark Mode Breaking (\rm{DMB}) conditions under these two parameters leads to multi-paths bipartite and tripartite entanglements. For a fine tuning of the polarization angle (φ=π/4) this scheme enables a generation of twin entangled states, where the bipartite/tripartite generated entangled states are degenerated and might be of great interest for quantum information processing, quantum communication and diverse quantum computational tasks. The generated entanglements are more resilient against thermal fluctuations in the \rm{DMB} regime, i.e., up to two order of magnitude robust than in the Unbreaking regime. Our work sheets light on new possibilities to generate noise-tolerant quantum resources that are useful for plethora of modern quantum technologies.
Quantum entanglement not only plays an important role in the study of the fundamentals of quantum theory, but also is considered as a crucial resource in quantum information science. The generation of macroscopic entanglement involving multiple optical and mechanical modes is a desired task in cavity optomechanics. However, the dark-mode effect is a critical obstacle against the generation of quantum entanglement in multimode optomechanical systems consisting of multiple degenerate or near-degenerate mechanical modes coupled to a common cavity mode. Here we propose an auxiliary-cavity-mode method to enhance optomechanical entanglement in a multimode optomechanical system by breaking the dark-mode effect. We find that the introduction of the auxiliary cavity mode not only assists the entanglement creation between the cavity mode and the mechanical modes, but also improves the immunity of the optomechanical entanglement to the thermal excitations by about three orders of magnitude. We also study the optomechanical entanglement in the network-coupled optomechanical system consisting of two mechanical modes and two cavity modes. By analyzing the correspondence between the optomechanical entanglement and the dark-mode effect, we find that optomechanical entanglement can be largely enhanced once the dark mode is broken. In addition, we study the mechanical entanglement and find that it is negligibly small. We also present some discussions on the experimental implementation with a microwave optomechanical setup, on the relationship between the dark-mode-breaking mechanism and the center-of-mass and relative coordinates, and on the explanation of the important role of the dark-mode breaking in the enhancement of optomechanical entanglement. Our results pave the way towards the preparation of entangled optomechanical networks and noise-resistant quantum resources.
We propose a novel scheme to generate and manipulate bipartite and tripartite entanglement and Bell nonlocality in a closed-loop three-mode optomechanical system, where two optical modes are simultaneously coupled to a mechanical mode via typical optomechanical interactions and also coupled to each other through field transmission. This configuration gives rise to a phase-sensitive coupling, in which the relative phase directly controls the population distribution between two optical modes, enabling coherent redistribution of quantum correlations. By tuning this relative phase, we achieve deterministic switching of bipartite entanglement between two optical-mechanical pairs, as well as tunable genuine tripartite entanglement among three modes. Employing the displaced-parity measurement, we construct both the bipartite and tripartite Bell inequalities in phase space and observe maximal violations of approximately 2.32 and 3, respectively, which coincide exactly with the values achievable for ideal bipartite and tripartite Einstein-Podolsky-Rosen states. Counterintuitively, we find that the tripartite Bell nonlocality can persist even when the genuine tripartite entanglement is absent, providing deeper insight into the relationship between these two types of quantum correlations. Furthermore, we systematically analyze the effects of mechanical dissipation and thermal noise, identifying the parameter regions where Bell violation survives under realistic experimental conditions. Our results establish a comprehensive framework for generating, controlling, and verifying multipartite quantum correlations, paving the way towards phase-tunable quantum networks and noise-resilient tests of quantum foundations.
ABSTRACT Quantum entanglement is a crucial resource in quantum information science, applying to quantum key distribution, quantum sensing, and quantum teleportation. However, generating macroscopic quantum entanglement in multimode optomechanical systems, where an optical mode couples to multiple degenerate or near‐degenerate vibrational modes, is a challenging task, as the entanglement is suppressed by the dark‐mode effect. In this paper, we propose a scheme to generate both bipartite and genuine tripartite entanglement in the system via periodic modulation. First, we consider a two‐oscillator optomechanical system in which time‐varying voltages applied to the oscillators enable the engineering of coupling pathways between the bright and dark modes, thus breaking the dark‐mode effect. Thermal phonons can be extracted by the coupling channels, so that bipartite and tripartite entanglement can be achieved at a nonzero temperature. Furthermore, we extend this scheme to an optomechanical system with oscillators, where the degenerate vibrational modes can entangle with the optical mode. Notably, the macroscopic quantum entanglement we obtain exhibits greater robustness against thermal phonons.