Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum-feedback-controlled macroscopic quantum nonlocality in cavity
  optomechanics   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 a 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
because the feedback drives the mechanical oscillators into a steady
approximate two-mode squeezed vacuum state, with arbitrary squeezing in
principle. It is shown that the feedback can also obviously improve the purity
of the nonclassical mechanical states. The dependences of the mechanical
quantum nonlocality on the feedback strength and thermal fluctuations are
studied, and it is found that Bell nonlocality is much more vulnerable to
thermal noise than EPR steerable nonlocality.

32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph