Optomechanically Entangled

Huang Jian, Deng-Gao Lai, Jie‐Qiao Liao

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.

David S. Simon

Dan Zhang, Xiaoping Zhang, Qiang Zheng

We theoretically investigate the stationary entanglement of a optomechanical system with an additional Kerr medium in the cavity. There are two kinds of interactions in the system, photon—mirror interaction and photon—photon interaction. The optomechanical entanglement created by the former interaction can be effectively controlled by the latter one. We find that the optomechanical entanglement is suppressed by Kerr interaction due to photon blockage. We also find that the Kerr interaction can create the stationary entanglement and induce the resonance of entanglement in the small detuning regime. These results show that the Kerr interaction is an effective control for the optomechanical system.

David S. Simon

Qizhi Cai, Boyu Fan, Yunru Fan +5 more

A scheme for the generation of steady-state entanglement between optical and mechanical cavity modes in an optomechanical crystal nanobeam is proposed. Based on finite element simulation and the quantum Langevin equation, we explore the evolution of entanglement with optomechanical properties in various device configurations, and demonstrate the ability of optimal entanglement generation in both blue and red detuned optical pumps. The intrinsic relationship between optomechanical cooperativity and entanglement is further clarified for depicting a clear physical picture of optomechanical interaction. Our work expands the understanding of macroscopic quantum mechanics and is an important step for developing novel quantum optomechanical devices.