6,839 research outputs found
Quantum non-demolition measurement of nonlocal variables and its application in quantum authentication
Quantun non-demolition (QND) variables are generlized to the nonlocal ones by
proposing QND measurement networks of Bell states and multi-partite GHZ states,
which means that we can generate and measure them without any destruction. One
of its prospective applications in the quantum authentication system of the
Quantum Security Automatic Teller Machine (QSATM) which is much more reliable
than the classical ones is also presented.Comment: 5 Pages, 3 Figure
Basic limitations for entanglement catalysis
In this paper we summarize the necessary condition for incomparable states
which can be catalyzed under entanglement-assisted LQCC (ELQCC). When we apply
an extended condition for entanglement transformation to entanglement-assisted
local manipulation we obtain a fundamental limit for entanglement catalysts.
Some relative questions are also discussed.Comment: 4 pages, revtex, no figure
Multi-step quantum secure direct communication using multi-particle Green-Horne-Zeilinger state
A multi-step quantum secure direct communication protocol using blocks of
multi-particle maximally entangled state is proposed. In this protocol, the
particles in a Green-Horne-Zeilinger state are sent from Alice to Bob in
batches in several steps. It has the advantage of high efficiency and high
source capacity.Comment: 4 pages and 1 figure. Revised version of Optics Communications 253
(2005(1
Information filtering via biased heat conduction
Heat conduction process has recently found its application in personalized
recommendation [T. Zhou \emph{et al.}, PNAS 107, 4511 (2010)], which is of high
diversity but low accuracy. By decreasing the temperatures of small-degree
objects, we present an improved algorithm, called biased heat conduction (BHC),
which could simultaneously enhance the accuracy and diversity. Extensive
experimental analyses demonstrate that the accuracy on MovieLens, Netflix and
Delicious datasets could be improved by 43.5%, 55.4% and 19.2% compared with
the standard heat conduction algorithm, and the diversity is also increased or
approximately unchanged. Further statistical analyses suggest that the present
algorithm could simultaneously identify users' mainstream and special tastes,
resulting in better performance than the standard heat conduction algorithm.
This work provides a creditable way for highly efficient information filtering.Comment: 4 pages, 3 figure
Quantum data hiding with spontaneous parameter down-conversion
Here we analyze the practical implication of the existing quantum data hiding
protocol with Bell states produced with optical downconverter. We show that the
uncertainty for the producing of the Bell states with spontaneous parameter
down-conversion should be taken into account, because it will cause serious
trouble to the hider encoding procedure. A set of extended Bell states and a
generalized Bell states analyzer are proposed to describe and analyze the
possible states of two photons distributing in two paths. Then we present a
method to integrate the above uncertainty of Bell states preparation into the
dating hiding procedure, when we encode the secret with the set of extended
Bell states. These modifications greatly simplify the hider's encoding
operations, and thus paves the way for the implementation of quantum data
hiding with present-day quantum optics.Comment: 4 pages, 1 figure, adding some analyse for security proof, to be
appear in Phys. Rev.
Quantum secret sharing without entanglement
After analysing the main quantum secret sharing protocol based on the
entanglement states, we propose an idea to directly encode the qubit of quantum
key distributions, and then present a quantum secret sharing scheme where only
product states are employed. As entanglement, especially the inaccessable
multi-entangled state, is not necessary in the present quantum secret sharing
protocol, it may be more applicable when the number of the parties of secret
sharing is large. Its theoretic efficiency is also doubled to approach 100%.Comment: 2 tables, to appear in Phys. Lett.
A Last Look at the Microwave Haze/Bubbles with WMAP
The microwave "haze" was first discovered with the initial release of the
full sky data from the Wilkinson Microwave Anisotropy Probe. It is diffuse
emission towards the center of our Galaxy with spectral behavior that makes it
difficult to categorize as any of the previously known emission mechanisms at
those wavelengths. With now seven years of WMAP data publicly available, we
have learned much about the nature of the haze, and with the release of data
from the Fermi Gamma-Ray Space Telescope and the discovery of the gamma-ray
haze/bubbles, we have had a spectacular confirmation of its existence at other
wavelengths. As the WMAP mission winds down and the Planck mission prepares to
release data, I take a last look at what WMAP has to tell us about the origin
of this unique Galactic feature. Much like the gamma-rays, the microwave
haze/bubbles is elongated in latitude with respect to longitude by a factor of
roughly two, and at high latitudes, the microwave emission cuts off sharply
above ~35 degrees (compared to ~50 degrees in the gammas). The hard spectrum of
electrons required to generate the microwave synchrotron is consistent with
that required to generate the gamma-ray emission via inverse Compton
scattering, though it is likely that these signals result from distinct regions
of the spectrum (~10 GeV for the microwaves, ~1 TeV for the gammas). While
there is no evidence for significant haze polarization in the 7-year WMAP data,
I demonstrate explicitly that it is unlikely such a signal would be detectable
above the noise.Comment: 9 pages, 6 figures; accepted in ApJ; matches published version with
significantly enhanced figure
Preparation of multi-party entanglement of individual photons and atomic ensembles
An experimental feasible scheme is proposed to generate
Greenberger-Horne-Zeilinger (GHZ) type of maximal entanglement. Distinguishing
from the previous schemes, this entanglement can be chosen between either
atomic ensembles (stationary qubit) or individual photons (flying qubit),
according to the difference applications we desire for it. The physical
requirements of the scheme are moderate and well fit the present experimental
techinque.Comment: 4 pages, 3 figures,minor clarification to the Fig.
A novel quantum key distribution scheme with orthogonal product states
The general conditions for the orthogonal product states of the multi-state
systems to be used in quantum key distribution (QKD) are proposed, and a novel
QKD scheme with orthogonal product states in the 3x3 Hilbert space is
presented. We show that this protocol has many distinct features such as great
capacity, high efficiency. The generalization to nxn systems is also discussed
and a fancy limitation for the eavesdropper's success probability is reached.Comment: 4 Pages, 3 Figure
Nonlocal Gate Of Quantum Network Via Cavity Quantum Electrodynamics
We propose an experimentally feasible scheme to realize the nonlocal gate
between two different quantum network nodes. With an entanglement-qubit (ebit)
acts as a quantum channel, our scheme is resistive to actual environment noise
and can get high fidelity in current cavity quantum electrodynamics (C-QED)
system.Comment: 5 pages, 3 figures, 1 tabl
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