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