3,912 research outputs found
A sufficient Entanglement Criterion Based On Quantum Fisher Information and Variance
We derive criterion in the form of inequality based on quantum Fisher
information and quantum variance to detect multipartite entanglement. It can be
regarded as complementary of the well-established PPT criterion in the sense
that it can also detect bound entangled states. The inequality is motivated by
Y.Akbari-Kourbolagh [Phys. Rev A. 99, 012304 (2019)] which introduced
a multipartite entanglement criterion based on quantum Fisher information. Our
criterion is experimentally measurable for detecting any -qudit pure state
mixed with white noisy. We take several examples to illustrate that our
criterion has good performance for detecting certain entangled states.Comment: 11 pages, 1 figur
A thermal quench induces spatial inhomogeneities in a holographic superconductor
Holographic duality is a powerful tool to investigate the far-from
equilibrium dynamics of superfluids and other phases of quantum matter. For
technical reasons it is usually assumed that, after a quench, the far-from
equilibrium fields are still spatially uniform. Here we relax this assumption
and study the time evolution of a holographic superconductor after a
temperature quench but allowing spatial variations of the order parameter. Even
though the initial state and the quench are spatially uniform we show the order
parameter develops spatial oscillations with an amplitude that increases with
time until it reaches a stationary value. The free energy of these
inhomogeneous solutions is lower than that of the homogeneous ones. Therefore
the former corresponds to the physical configuration that could be observed
experimentally.Comment: corrected typos, added references and new results for a different
quenc
Normal modes and time evolution of a holographic superconductor after a quantum quench
We employ holographic techniques to investigate the dynamics of the order
parameter of a strongly coupled superconductor after a perturbation that drives
the system out of equilibrium. The gravity dual that we employ is the Soliton background at zero temperature. We first analyze the normal
modes associated to the superconducting order parameter which are purely real
since the background has no horizon. We then study the full time evolution of
the order parameter after a quench. For sufficiently a weak and slow
perturbation we show that the order parameter undergoes simple undamped
oscillations in time with a frequency that agrees with the lowest normal model
computed previously. This is expected as the soliton background has no horizon
and therefore, at least in the probe and large limits considered, the
system will never return to equilibrium. For stronger and more abrupt
perturbations higher normal modes are excited and the pattern of oscillations
becomes increasingly intricate. We identify a range of parameters for which the
time evolution of the order parameter become quasi chaotic. The details of the
chaotic evolution depend on the type of perturbation used. Therefore it is
plausible to expect that it is possible to engineer a perturbation that leads
to the almost complete destruction of the oscillating pattern and consequently
to quasi equilibration induced by superposition of modes with different
frequencies.Comment: 10 pages, 7 figures, corrected typos, expanded section on chaotic
oscillations and new results for other quenc
Entropic uncertainty relations with quantum memory in a multipartite scenario
Entropic uncertainty relations demonstrate the intrinsic uncertainty of
nature from an information-theory perspective. Recently, a
quantum-memory-assisted entropic uncertainty relation for multiple measurements
was proposed by Wu [Phys Rev A. 106. 062219 (2022)]. Interestingly,
the quantum-memory-assisted entropic uncertainty relation for multiple
measurement settings can be further generalized. In this work, we propose two
complementary multipartite quantum-memory-assisted entropic uncertainty
relations and our lower bounds depend on values of complementarity of the
observables, (conditional) von-Neumann entropies, Holevo quantities, and mutual
information. As an illustration, we provide several typical cases to exhibit
that our bounds are tighter and outperform the previous bounds.Comment: 7 pages, 3 figure
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