Generation of Quantum Entanglement in a Multimode Cavity‐Optomechanical System via Periodic Modulation

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.