21,714 research outputs found
Extracting Classical Correlations from a Bipartite Quantum System
In this paper we discuss the problem of splitting the total correlations for
a bipartite quantum state described by the Von Neumann mutual information into
classical and quantum parts. We propose a measure of the classical correlations
as the difference between the Von Neumann mutual information and the relative
entropy of entanglement. We compare this measure with different measures
proposed in the literature.Comment: 5 pages, 1 figur
Foundations of Quantum Discord
This paper summarizes the basics of the notion of quantum discord and how it
relates to other types of correlations in quantum physics. We take the
fundamental information theoretic approach and illustrate our exposition with a
number of simple examples.Comment: 3 pages, special issue edited by Diogo de Oliveira Soares Pinto et a
Solitary waves and yrast states in Bose-Einstein condensed gases of atoms
Considering a Bose-Einstein condensed gas confined in one dimension with
periodic boundary conditions, we demonstrate that, very generally,
solitary-wave and rotational excitations coincide. This exact equivalence
allows us to establish connections between a number of effects that are present
in these two problems, many of which have been studied using the mean-field
approximation.Comment: Revised version, where the generality of our arguments is presented
more clearl
Classical, quantum and total correlations
We discuss the problem of separating consistently the total correlations in a
bipartite quantum state into a quantum and a purely classical part. A measure
of classical correlations is proposed and its properties are explored.Comment: 10 pages, 3 figure
The H1 Forward Track Detector at HERA II
In order to maintain efficient tracking in the forward region of H1 after the
luminosity upgrade of the HERA machine, the H1 Forward Track Detector was also
upgraded. While much of the original software and techniques used for the HERA
I phase could be reused, the software for pattern recognition was completely
rewritten. This, along with several other improvements in hit finding and
high-level track reconstruction, are described in detail together with a
summary of the performance of the detector.Comment: Minor revision requested by journal (JINST) edito
The OLYMPUS Internal Hydrogen Target
An internal hydrogen target system was developed for the OLYMPUS experiment
at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled,
tubular cell within an aluminum scattering chamber. Hydrogen entered at the
center of the cell and exited through the ends, where it was removed from the
beamline by a multistage pumping system. A cryogenic coldhead cooled the target
cell to counteract heating from the beam and increase the density of hydrogen
in the target. A fixed collimator protected the cell from synchrotron radiation
and the beam halo. A series of wakefield suppressors reduced heating from beam
wakefields. The target system was installed within the DORIS storage ring and
was successfully operated during the course of the OLYMPUS experiment in 2012.
Information on the design, fabrication, and performance of the target system is
reported.Comment: 9 pages, 13 figure
Precision planar drift chambers and cradle for the TWIST muon decay spectrometer
To measure the muon decay parameters with high accuracy, we require an array
of precision drift detector layers whose relative position is known with very
high accuracy. This article describes the design, construction and performance
of these detectors in the TWIST (TRIUMF Weak Interaction Symmetry Test)
spectrometer.Comment: 44 pages, 16 Postscript figures, LaTeX2e, uses Elsevier class
elsart.cls, package graphicx, submitted to Nuclear Instruments & Methods in
Physics Researc
Invariant quantum discord in qubit-qutrit systems under local dephasing
We investigate the dynamics of quantum discord and entanglement for a
class of mixed qubit-qutrit states assuming that only the qutrit is under the action of a dephasing channel. We demonstrate that even though the entanglement in the qubit-qutrit state disappears in a finite time interval, partial coherence left in the system enables quantum discord to remain invariant throughout the whole time evolution
Teleportation as a Depolarizing Quantum Channel, Relative Entropy and Classical Capacity
We show that standard teleportation with an arbitrary mixed state resource is
equivalent to a generalized depolarizing channel with probabilities given by
the maximally entangled components of the resource. This enables the usage of
any quantum channel as a generalized depolarizing channel without additional
twirling operations. It also provides a nontrivial upper bound on the
entanglement of a class of mixed states. Our result allows a consistent and
statistically motivated quantification of teleportation success in terms of the
relative entropy and this quantification can be related to a classical
capacity.Comment: Version published in Phys. Rev. Let
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