4,643 research outputs found
All-versus-nothing violation of local realism in the one-dimensional Ising model
We show all-versus-nothing proofs of Bell's theorem in the one-dimensional
transverse-field Ising model, which is one of the most important exactly
solvable models in the field of condensed matter physics. Since this model can
be simulated with nuclear magnetic resonance, our work might lead to a fresh
approach to experimental test of the Greenberger-Horne-Zeilinger contradiction
between local realism and quantum mechanics.Comment: 4 page
Tight Correlation-Function Bell Inequality for Multipartite -Dimensional System
We generalize the correlation functions of the Clauser-Horne-Shimony-Holt
(CHSH) inequality to multipartite d-dimensional systems. All the Bell
inequalities based on this generalization take the same simple form as the CHSH
inequality. For small systems, numerical results show that the new inequalities
are tight and we believe this is also valid for higher dimensional systems.
Moreover, the new inequalities are relevant to the previous ones and for
bipartite system, our inequality is equivalent to the
Collins-Gisin-Linden-Masser-Popescu (CGLMP) inequality.Comment: 4 pages; Accepted by PR
New Constraint on the Parameters in Cabibbo-Kobayashi-Maskawa Matrix of Wolfenstein's Parametrization
Based on the relation between CP-violation phase and the other three mixing
angles in Cabibbo-Kobayashi-Maskawa matrix postulated by us before, a new
constraint on the parameters of Wolfenstein's parametrization is given. The
result is consistent with the relative experimental results and can be further
put to the more precise tests in future.Comment: 5 pages, Latex file, the final revised version for submittin
Quantifying Nonlocality Based on Local Hidden Variable Models
We introduce a fresh scheme based on the local hidden variable models to
quantify nonlocality for arbitrarily high-dimensional quantum systems. Our
scheme explores the minimal amount of white noise that must be added to the
system in order to make the system local and realistic. Moreover, the scheme
has a clear geometric significance and is numerically computable due to
powerful computational and theoretical methods for the class of convex
optimization problems known as semidefinite programs.Comment: 4page
SO(4) symmetry in the relativistic hydrogen atom
We show that the relativistic hydrogen atom possesses an SO(4) symmetry by
introducing a kind of pseudo-spin vector operator. The same SO(4) symmetry is
still preserved in the relativistic quantum system in presence of an U(1)
monopolar vector potential as well as a nonabelian vector potential. Lamb shift
and SO(4) symmetry breaking are also discussed.Comment: 4 pages, 1 figur
Maximal Quantum Violation of the CGLMP Inequality on Its Both Sides
We investigate the maximal violations for both sides of the -dimensional
CGLMP inequality by using the Bell operator method. It turns out that the
maximal violations have a decelerating increase as the dimension increases and
tend to a finite value at infinity. The numerical values are given out up to
for positively maximal violations and for negatively
maximal violations. Counterintuitively, the negatively maximal violations tend
to be a little stronger than the positively maximal violations. Further we show
the states corresponding to these maximal violations and compare them with the
maximally entangled states by utilizing entangled degree defined by von Neumann
entropy. It shows that their entangled degree tends to some nonmaximal value as
the dimension increases.Comment: 14 pages, 2 figures. Accepted for publication in International
Journal of Quantum Informatio
Bell Inequality Based on Peres-Horodecki Criterion
We established a physically utilizable Bell inequality based on the
Peres-Horodecki criterion. The new quadratic probabilistic Bell inequality
naturally provides us a necessary and sufficient way to test all entangled
two-qubit or qubit-qutrit states including the Werner states and the maximally
entangled mixed states.Comment: 4 pages, 2 figures. Revised version. Title and Figures changed,
references adde
Quantum backflow in solutions to the Dirac equation of the spin- free particle
It was known that a free, nonrelativistic particle in a superposition of
positive momenta can, in certain cases, bear a negative probability current ---
hence termed quantum backflow. Here, it is shown that more variations can be
brought about for a free Dirac particle, particularly when negative-energy
solutions are taken into account. Since any Dirac particle can be understood as
an antiparticle that acts oppositely (and vice versa), quantum backflow is
found to arise in the superposition (i) of a well-defined momentum but
different signs of energies, or more remarkably (ii) of different signs of both
momenta and energies. Neither of these cases has counterpart in nonrelativistic
quantum mechanics. A generalization by using the field-theoretic formalism is
also presented and discussed.Comment: 5 pages, 1 figur
On realizing Lov\'asz-optimum orthogonal representation in the real Hilbert space
Quantum contextuality is usually revealed by the non-contextual inequality,
which can always be associated with an exclusivity graph. The quantum upper
bound of the inequality is nothing but the Lov\'asz number of the graph. In
this work, we show that if there is a Lov\'asz-optimum orthogonal
representation realized in the -dimensional complex Hilbert space, then
there always exists a corresponding Lov\'asz-optimum orthogonal representation
in the -dimensional real Hilbert space. This in turn completes the
proof that the Lov\'asz-optimum orthogonal representation for any exclusivity
graph can always be realized in the real Hilbert space of suitable dimension
Connecting quantum contextuality and genuine multipartite nonlocality with the quantumness witness
The Clauser-Horne-Shimony-Holt-type noncontextuality inequality and the
Svetlichny inequality are derived from the Alicki-Van Ryn quantumness witness.
Thus a connection between quantumness and quantum contextuality, and that
between quantumness and genuine multipartite nonlocality, are established.Comment: 4 pages. Accpeted in Chin. Phys. Let
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