In this paper, we propose a continuous measurement and feedback scheme to achieve strong Einstein–Podolsky–Rosen (EPR) steering and Bell nonlocality of two macroscopic mechanical oscillators in cavity optomechanics. Our system consists of two optomechanical cavities in which two cavity fields are coupled to each other via nondegenerate parametric downconversion. The two cavity output fields are subject to continuous Bell-like homodyne detection and the detection currents are fed back to drive the cavity fields. It is found that when the feedback is absent, the two mechanical oscillators can only be prepared in steady weakly entangled states which however do not display EPR steering and Bell nonlocality, due to the so-called 3 dB limit. But when the feedback is present, it is found that the mechanical entanglement is considerably enhanced such that strong mechanical steering and Bell nonlocality can be obtained in the steady-state regime. We analytically reveal that this is becau...

中文翻译：

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腔光机中的量子反馈控制宏观量子非局部性

在本文中，我们提出了一种连续测量和反馈方案，以实现腔光学机械中两个宏观机械振荡器的强爱因斯坦-波多尔斯基-罗森（EPR）转向和贝尔非局部性。我们的系统由两个光机械腔组成，其中两个腔场通过非简并参量下转换彼此耦合。两个空腔输出场都经过连续的贝尔式零差检测，并且检测电流被反馈以驱动空腔场。已经发现，当没有反馈时，两个机械振荡器只能在稳定的弱纠缠状态下准备，但是由于所谓的3 dB限制，因此不会显示EPR转向和贝尔非局部性。但是当有反馈时，我们发现机械缠结得到了极大的增强，从而在稳态状态下可以获得很强的机械转向和Bell非局部性。我们分析地表明这是美丽的...