3,859 research outputs found
Quantum resource studied from the perspective of quantum state superposition
Quantum resources,such as discord and entanglement, are crucial in quantum
information processing. In this paper, quantum resources are studied from the
aspect of quantum state superposition. We define the local superposition (LS)
as the superposition between basis of single part, and nonlocal superposition
(NLS) as the superposition between product basis of multiple parts. For quantum
resource with nonzero LS, quantum operation must be introduced to prepare it,
and for quantum resource with nonzero NLS, nonlocal quantum operation must be
introduced to prepare it. We prove that LS vanishes if and only if the state is
classical and NLS vanishes if and only if the state is separable. From this
superposition aspect, quantum resources are categorized as superpositions
existing in different parts. These results are helpful to study quantum
resources from a unified frame.Comment: 9 pages, 4 figure
Entanglement and quantum discord dynamics of two atoms under practical feedback control
We study the dynamics of two identical atoms resonantly coupled to a
single-mode cavity under practical feedback control, and focus on the detection
inefficiency. The entanglement is induced to vanish in finite time by the
inefficiency of detection. Counterintuitively, the asymptotic entanglement and
quantum discord can be increased by the inefficiency of detection. The noise of
detection triggers control field to create entanglement and discord when no
photon are emitted from the atoms. Furthermore, sudden change happens to the
dynamics of entanglement.Comment: 5 pages, 4 figure
Strong Cosmic Censorship in Charged de Sitter spacetime with Scalar Field Non-minimally Coupled to Curvature
We examine the stability and the strong cosmic censorship in the
Reissner-Nordstrom-de Sitter (RN-dS) black hole by investigating the evolution
of a scalar field non-minimally coupled to the curvature. We find that when the
coupling parameter is negative, the RN-dS black hole experiences instability.
The instability disappears when the coupling parameter becomes non-negative.
With the increase of the coupling parameter, the violation of the strong cosmic
censorship occurs at a larger critical charge ratio. But such an increase of
the critical charge is suppressed by the increase of the cosmological constant.
Different from the minimal coupling situation, it is possible to accommodate
in the near extremal black hole when the scalar field is
non-minimally coupled to curvature. The increase of the cosmological constant
can allow to be satisfied for even smaller value of the coupling
parameter. The existence of implies that the resulting curvature
can continuously cross the Cauchy horizon.Comment: 14 pages, 4 figures, 5 table
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