Creation of Entanglement with Nonlocal Operations

We discuss how to create more entanglement with nonlocal operations acting on two-particle states. For a given nonlocal operation, we find that some input states cannot produce entanglement and some produce the maximal entanglement, and find that any initial entangled states can produce more entanglement than initial product states.     

Generic security analysis framework for quantum secure direct communication

Quantum secure direct communication provides a direct means of conveying secret information via quantum states among legitimate users. The past two decades have witnessed its great strides both theoretically and experimentally. However, the security analysis of it still stays in its infant. Some practical problems in this field to be solved urgently, such as detector efficiency mismatch, side-channel effect and source imperfection, are propelling the birth of a more impeccable solution. In this paper, we establish a new framework of the security analysis driven by numerics where all the practical problems may be taken into account naturally. We apply this framework to several variations of the DL04 protocol considering real-world experimental conditions. Also, we propose two optimizing methods to process the numerical part of the framework so as to meet different requirements in practice. With these properties considered, we predict the robust framework would open up a broad avenue of the development in the field.     

Quantum Privacy Amplification for a Sequence of Single Qubits

We present a scheme for quantum privacy amplification (QPA) for a sequence of single qubits. The QPA procedure uses a unitary operation with two controlled-not gates and a Hadamard gate. Every two qubits are performed with the unitary gate operation, and a measurement is made on one photon and the other one is retained.The retained qubit carries the state information of the discarded one. In this way, the information leakage is reduced.The procedure can be performed repeatedly so that the information leakage is reduced to any arbitrarily low level. With this QPA scheme, the quantum secure direct communication with single qubits can be implemented with arbitrarily high security. We also exploit this scheme to do privacy amplification on the single qubits in quantum information sharing for long-distance communication with quantum repeaters.     

Multiple Entropy Measures for Multi-particle Pure Quantum Statet

We propose to use a set of averaged entropies, the multiple entropy measures （MEMS）, to partially quantify quantum entanglement of multipartite quantum state. The MEMS is vector-like with m = [N/2] components： [S1, S2,..., Sm], and the i-th component Si is the geometric mean of i-qubits partial entropy of the system. The Si measures how strong an arbitrary i qubits from the system are correlated with the rest of the system. It satisfies the conditions for a good entanglement measure. We have analyzed the entanglement properties of the GHZ-state, the W-states, and cluster-states under MEMS.     

High-Dimensional Multi-particle Cat-Like State Teleportation

Two kinds of M-particle d-dimensional Schmidt-form entangled state teleportation protocols are presented.In the first protocol, the teleportation is achieved by d-dimensional Bell-basis measurements, while in the second protocolit is realized by d-dimensional GHZ-basis measurement.     

Some New Solutions of Jacobi Elliptic Functions to mBBM Equation

The modified mapping method is further improved by the expanded expression of u（ξ） that contains the terms of the first-order derivative of function f（ξ）. Some new exact solutions to the mBBM equation are determined by means of the method. We can obtain many new solutions in terms of the Jacobi elliptic functions of the equation.     

General Decoherence Suppression in Three-Level Atom in V- and Ξ-Configurations

In this paper, we present the decoupling bang-bang （BB） twin-born pulses to suppress the genera/deco- herence, both amplitude and phase decoherence, in a three-level atom in V- and Ξ-configurations. We give the exact sequence of periodic twinborn pulses in such systems.     

Quantum Privacy Amplification for a Sequence of Single Qubits

We present a scheme for quantum privacy amplification （QPA） for a sequence of single qubits. The QPA procedure uses a unitary operation with two controlled-not gates and a Hadamard gate. Every two qubits are performed with the unitary gate operation, and a measurement is made on one photon and the other one is retained. The retained qubit carries the state information of the discarded one. In this way, the information leakage is reduced. The procedure can be performed repeatedly so that the information leakage is reduced to any arbitrarily low level. With this QPA scheme, the quantum secure direct communication with single qubits can be implemented with arbitrarily high security. We also exploit this scheme to do privacy amplification on the single qubits in quantum information sharing for long-distance communication with quantum repeaters.     

General Quantum Interference Principle and Duality Computer

In this article, we propose a general principle of quantum interference for quantum system, and based on this we propose a new type of computing machine, the duality computer, that may outperform in principle both classical computer and the quantum computer. According to the general principle of quantum interference, the very essence of quantum interference is the interference of the sub-waves of the quantum system itself. A quantum system considered here can be any quantum system: a single microscopic particle, a composite quantum system such as an atom or a molecule, or a loose collection of a few quantum objects such as two independent photons. In the duality computer, the wave of the duality computer is split into several sub-waves and they pass through different routes, where different computing gate operations are performed. These sub-waves are then re-combined to interfere to give the computational results. The quantum computer, however, has only used the particle nature of quantum object. In a duality computer, it may be possible to find a marked item from an unsorted database using only a single query, and all NP-complete problems may have polynomial algorithms. Two proof-of-the-principle designs of the duality computer are presented: the giant molecule scheme and the nonlinear quantum optics scheme. We also propose thought experiment to check the related fundamental issues, the measurement efficiency of a partial wave function.     

Mixed Symmetry States in Even—Even ^96—108Mo Nuclei

Excitation energies and electromagnetic transition strengths in even-even ^96-108Mo nuclei have been described systematically be using the proton-neutron interacting boson model (IBM-2).It appears that the properties of low-lying levels in these isotopes,for which the comparison between experiment and theory is possible,can be satisfactorily described by the IBM-2 model,provided proper account is taken of the presence at low energy of states having a mixed-symmetry character.It seems possible to identify,in each isotope,a few states having such a character,the lowest ones being either 22^ or 23^ levels.It is found that these nuclei are in the transition from U(5) to SU(3).