Quantum secret sharing between m-party and n-party with six states

We propose a quantum secret sharing scheme between $m$-party and $n$-party using three conjugate bases, i.e. six states. A sequence of single photons, each of which is prepared in one of the six states, is used directly to encode classical information in the quantum secret sharing process. In this scheme, each of all $m$ members in group 1 choose randomly their own secret key individually and independently, and then directly encode their respective secret information on the states of single photons via unitary operations, then the last one (the $m$th member of group 1) sends $1/n$ of the resulting qubits to each of group 2. By measuring their respective qubits, all members in group 2 share the secret information shared by all members in group 1. The secret message shared by group 1 and group 2 in such a way that neither subset of each group nor the union of a subset of group 1 and a subset of group 2 can extract the secret message, but each whole group (all the members of each group) can. The scheme is asymptotically 100% in efficiency. It makes the Trojan horse attack with a multi-photon signal, the fake-signal attack with EPR pairs, the attack with single photons, and the attack with invisible photons to be nullification. We show that it is secure and has an advantage over the one based on two conjugate bases. We also give the upper bounds of the average success probabilities for dishonest agent eavesdropping encryption using the fake-signal attack with any two-particle entangled states. This protocol is feasible with present-day technique.Comment: 7 page

Circular quantum secret sharing

A circular quantum secret sharing protocol is proposed, which is useful and efficient when one of the parties of secret sharing is remote to the others who are in adjacent, especially the parties are more than three. We describe the process of this protocol and discuss its security when the quantum information carrying is polarized single photons running circularly. It will be shown that entanglement is not necessary for quantum secret sharing. Moreover, the theoretic efficiency is improved to approach 100% as almost all the instances can be used for generating the private key, and each photon can carry one bit of information without quantum storage. It is straightforwardly to utilize this topological structure to complete quantum secret sharing with multi-level two-particle entanglement in high capacity securely.Comment: 7 pages, 2 figure

Efficient quantum cryptography network without entanglement and quantum memory

An efficient quantum cryptography network protocol is proposed with d-dimension polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are |0>. The users code the information on the single photons with some unitary operations. For preventing the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique (decoy-photon technique) is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum state and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse.Comment: 4 pages, 1 figures. It also presented a way for preparing decoy photons without a sinigle-photon sourc

Efficient symmetric multiparty quantum state sharing of an arbitrary m-qubit state

We present a scheme for symmetric multiparty quantum state sharing of an arbitrary $m$-qubit state with $m$ Greenberger-Horne-Zeilinger states following some ideas from the controlled teleportation [Phys. Rev. A \textbf{72}, 02338 (2005)]. The sender Alice performs $m$ Bell-state measurements on her $2m$ particles and the controllers need only to take some single-photon product measurements on their photons independently, not Bell-state measurements, which makes this scheme more convenient than the latter. Also it does not require the parties to perform a controlled-NOT gate on the photons for reconstructing the unknown $m$-qubit state and it is an optimal one as its efficiency for qubits approaches the maximal value.Comment: 6 pages, no figures; It simplifies the process for sharing an arbitrary m-qubit state in Phys. Rev. A 72, 022338 (2005) (quant-ph/0501129

Probabilistic teleportation of unknown two-particle state via POVM

We propose a scheme for probabilistic teleportation of unknown two-particle state with partly entangled four-particle state via POVM. In this scheme the teleportation of unknown two-particle state can be realized with certain probability by performing two Bell state measurements, a proper POVM and a unitary transformation.Comment: 5 pages, no figur

De Novo Genome Sequence of "Candidatus Liberibacter solanacearum" from a Single Potato Psyllid in California.

The draft genome sequence of "Candidatus Liberibacter solanacearum" strain RSTM from a potato psyllid (Bactericera cockerelli) in California is reported here. The RSTM strain has a genome size of 1,286,787 bp, a G+C content of 35.1%, 1,211 predicted open reading frames (ORFs), and 43 RNA genes

The binary mass transfer origin of the red blue straggler sequence in M30

Two separated sequences of blue straggler stars (BSSs) have been revealed by Ferraro et al. (2009) in the color-magnitude diagram (CMD) of the Milky Way globular cluster M30. Their presence has been suggested to be related to the two BSS formation channels (namely, collisions and mass-transfer in close binaries) operating within the same stellar system. The blue sequence was indeed found to be well reproduced by collisional BSS models. In contrast, no specific models for mass transfer BSSs were available for an old stellar system like M30. Here we present binary evolution models, including case-B mass transfer and binary merging, specifically calculated for this cluster. We discuss in detail the evolutionary track of a $0.9+0.5 M_\odot$ binary, which spends approximately 4 Gyr in the BSS region of the CMD of a 13 Gyr old cluster. We also run Monte-Carlo simulations to study the distribution of mass transfer BSSs in the CMD and to compare it with the observational data. Our results show that: (1) the color and magnitude distribution of synthetic mass transfer BSSs defines a strip in the CMD that nicely matches the observed red BSS sequence, thus providing strong support to the mass transfer origin for these stars; (2) the CMD distribution of synthetic BSSs never attains the observed location of the blue BSS sequence, thus reinforcing the hypothesis that the latter formed through a different channel (likely collisions); (3) most ($\sim 60\%$) of the synthetic BSSs are produced by mass-transfer models, while the remaining $< 40\%$ requires the contribution from merger models.Comment: 8 pages, 5 figures, accepted to Ap

A large sample of low surface brightness disk galaxies from the SDSS. I: The sample and the stellar populations

We present the properties of a large sample (12,282) of nearly face-on low surface brightness (LSB) disk galaxies selected from the main galaxy sample of SDSS-DR4. These properties include B-band central surface brightness mu_0(B), scale lengths h, integrated magnitudes, colors, and distances D. This sample has mu_0(B) values from 22 to 24.5 mag arcsec^{-2} with a median value of 22.42 mag arcsec^{-2}, and disk scale lengths ranging from 2 to 19 kpc. They are quite bright with M_B taking values from -18 to -23 mag with a median value of -20.08 mag. There exist clear correlations between logh and M_B, logh and logD, logD and M_B. However, no obvious correlations are found between mu_0(B) and logh, colors etc. The correlation between colors and logh is weak even though it exists. Both the optical-optical and optical-NIR color-color diagrams indicate that most of them have a mixture of young and old stellar populations. They also satisfy color-magnitude relations, which indicate that brighter galaxies tend generally to be redder. The comparison between the LSBGs and a control sample of nearly face-on disk galaxies with higher surface brightness (HSB) with mu_0(B) from 18.5 to 22 mag arcsec^{-2} show that, at a given luminosity or distance, the observed LSB galaxies tend to have larger scale lengths. These trends could be seen gradually by dividing both the LSBGs and HSBGs into two sub-groups according to surface brightness. A volume-limited sub-sample was extracted to check the incompleteness of surface brightness. The only one of the property relations having an obvious change is the relation of logh versus mu_0(B), which shows a correlation in this sub-sample.Comment: 14 pages, 18 figures, accepted for publication in MNRA

Quantum secure direct communication network with superdense coding and decoy photons

A quantum secure direct communication network scheme is proposed with quantum superdense coding and decoy photons. The servers on a passive optical network prepare and measure the quantum signal, i.e., a sequence of the $d$-dimensional Bell states. After confirming the security of the photons received from the receiver, the sender codes his secret message on them directly. For preventing a dishonest server from eavesdropping, some decoy photons prepared by measuring one photon in the Bell states are used to replace some original photons. One of the users on the network can communicate any other one. This scheme has the advantage of high capacity, and it is more convenient than others as only a sequence of photons is transmitted in quantum line.Comment: 6 pages, 2 figur