3,723 research outputs found
Quantum secure communication protocols based on entanglement swapping
We present a quantum secure direct communication protocol and a multiparty
quantum secret sharing protocol based on Einstein-Podolsky-Rosen pairs and
entanglement swapping. The present quantum secure direct communication protocol
makes use of the ideal of block transmission. We also point out that the sender
can encode his or her secret message without ensuring the security of the
quantum channel firstly. In the multiparty quantum secret sharing protocol, the
communication parties adopt checking mode or encoding mode with a certain
probability. It is not necessary for the protocol to perform local unitary
operation. In both the protocols, one party transmits only one photon for each
Einstein-Podolsky-Rosen pair to another party and the security for the
transmitting photons is ensured by selecting Z-basis or X-basis randomly to
measure the sampling photons
Quantum secure direct communication with pure entangled states
We present a quantum secure direct communication protocol where the channels
are not maximally entangled states. The communication parties utilize decoy
photons to check eavesdropping. After ensuring the security of the quantum
channel, the sender encodes the secret message and transmits it to the receiver
by using Controlled-NOT operation and von Neumann measurement. The protocol is
simple and realizable with present technology. We also show the protocol is
secure for noisy quantum channel
Multiparty controlled quantum secret direct communication using Greenberger-Horne-Zeilinger state
Base on the idea of dense coding of three-photon entangled state and qubit
transmission in blocks, we present a multiparty controlled quantum secret
direct communication scheme using Greenberger-Horne-Zeilinger state. In the
present scheme, the sender transmits her three bits of secret message to the
receiver directly and the secret message can only be recovered by the receiver
under the permission of all the controllers. All three-photon entangled states
are used to transmit the secret messages except those chosen for eavesdropping
check and the present scheme has a high source capacity because
Greenberger-Horne-Zeilinger state forms a large Hilbert space
Efficient multiparty quantum secret sharing of secure direct communication
In this paper, we present an (n, n) threshold quantum secret sharing scheme
of secure direct communication using Greenberger-Horne-Zeilinger state. The
present scheme is efficient in that all the Greenberger-Horne-Zeilinger states
used in the quantum secret sharing scheme are used to generate shared secret
messages except those chosen for checking eavesdropper. In our scheme, the
measuring basis of communication parties is invariable and the classical
information used to check eavesdropping needs only the results of measurements
of the communication parties. Another nice feature of our scheme is that the
sender transmit her secret messages to the receivers directly and the receivers
recover the sender's secret by combining their results, different from the QSS
scheme whose object is essentially to allow a sender to establish a shared key
with the receivers. This feature of our scheme is similar to that of quantum
secret direct communication
Semiquantum secret sharing using two-particle entangled state
Recently, Boyer et al. presented a novel semiquantum key distribution
protocol [M. Boyer, D. Kenigsberg, and T. Mor, Phys. Rev. Lett. 99, 140501
(2007)], in which quantum Alice shares a secret key with classical Bob. Li et
al. proposed two semiquantum secret sharing protocols [Q. Li, W. H. Chan, and
D. Y. Long, Phys. Rev. A 82, 022303 (2010)] by using maximally entangled
Greenberger-Horne-Zeilinger states. In this paper, we present a semiquantum
secret sharing protocol by using two-particle entangled states in which quantum
Alice shares a secret key with two classical parties, Bob and Charlie.
Classical Bob and Charlie are restricted to performing measurement in the
computational basis, preparing a particle in the computational basis, or
reflecting the particles. None of them can acquire the secret unless they
collaborate. We also show the protocol is secure against eavesdropping.Comment: 8 page
Security proof of Counterfactual Quantum Cryptography against General Intercept-resend Attacks and Its Vulnerability
Counterfactual quantum cryptography (CQC), recently proposed by Noh, is
featured with no transmission of signal particles. This exhibits evident
security advantage, such as its immunity to the well known PNS attack. In this
paper, the theoretical security of CQC protocol against the general
intercept-resend attacks is proved by bounding the information of an
eavesdropper Eve more tightly than in Yin's proposal[Phys. Rev. A 82, 042335
(2010)]. It is also showed that practical CQC implementations may be vulnerable
when equipped with imperfect apparatuses, by proving that a negative key rate
can be achieved when Eve launches a time-shift attack based on imperfect
detector efficiency.Comment: 14 pages, 4 figure
Efficient spectral hole-burning and atomic frequency comb storage in Nd3+:YLiF4
We present spectral hole-burning measurements of the
transition in Nd:YLiF. The
isotope shifts of Nd can be directly resolved in the optical absorption
spectrum. We report atomic frequency comb storage with an echo efficiency of up
to 35% and a memory bandwidth of 60 MHz in this material. The interesting
properties show the potential of this material for use in both quantum and
classical information processing
The Higgs-Boson Decay to Order under the mMOM-Scheme
We study the decay width of the Higgs-boson up to order
under the minimal momentum space subtraction scheme (mMOM-scheme).
To improve the accuracy of perturbative QCD prediction, we adopt the principle
of maximum conformality (PMC) to set its renormalization scales. A detailed
comparison of the total decay width and the separate decay widths at each
perturbative order before and after the PMC scale setting is presented. The PMC
adopts the renormalization group equation to fix the optimal scales of the
process. After the PMC scale setting, the scale-dependence for both the total
and the separate decay widths are greatly suppressed, and the convergence of
perturbative QCD series is improved. By taking the Higgs mass GeV, as recently given by the ATLAS and CMS collaborations, we
predict keV,
where the first error is for Higgs mass and the second error is the residual
scale dependence by varying the initial scale .Comment: 9 pages, 3 figures. Revised version to be published in J.Phys.
QCD corrections to the to charmonia semi-leptonic decays
We present a detailed analysis on the meson semi-leptonic decays, , up to next-to-leading order (NLO) QCD
correction. We adopt the principle of maximum conformality (PMC) to set the
renormalization scales for those decays. After applying the PMC scale setting,
we determine the optimal renormalization scale for the
transition form factors (TFFs). Because of the same -terms, the
optimal PMC scales at the NLO level are the same for all those TFFs, i.e.
. We adopt a strong coupling model from
the massive perturbation theory (MPT) to achieve a reliable pQCD estimation in
this low energy region. Furthermore, we adopt a monopole form as an
extrapolation for the TFFs to all their allowable
region. Then, we predict , , , , where the uncertainties are squared averages of all the
mentioned error sources. We show that the present prediction of the production
cross section times branching ratio for relative to
that for , i.e. , is in a better
agreement with CDF measurements than the previous predictions.Comment: 11 pages, 5 figure
Exclusive charmonium production from annihilation round the peak
We make a comparative and comprehensive study on the charmonium exclusive
productions at the collider with the collision energy either round the
-boson mass for a super factory or equals to 10.6 GeV for the
factories as Belle and BABAR. We study the total cross sections for the
charmonium production via the exclusive processes and , where and
represent the dominant color-singlet -wave and -wave charmonium
states respectively. Total cross sections versus the collision energy
, together with their uncertainties, are presented, which clearly
show the relative importance of these channels. At the factory, the
production channels via the virtual propagator are dominant over the
channels via the propagator by about four orders. While, at the super
factory, due to the -boson resonance effect, the boson channels
shall provide sizable or even dominant contributions in comparison to the
channels via the propagator. Sizable exclusive charmonium events can
be produced at the super factory with high luminocity up to , especially for the channel of , e.g. by taking GeV, we shall have
,
, ,
,
, and events by one
operation year. Thus, in addition to the factories as BABAR and Belle, such
a super factory shall provide another useful platform for studying the
heavy quarkonium properties and for testing QCD theories.Comment: 19 pages, 9 figures. References and discussions updated. To be
published in Phys.Rev.
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