Liu Jin-ming

Multiparticle Generalization of Remote State Preparation

We present a scheme for preparing remotely a three-particle pure entangled state via entanglement swapping, and then we directly generalize it to the multiparticle case. It is shown that by using N pairs of bipartite EPR states as the quantum channel, remote preparation of some specially chosen N-particle pure entangled states can be achieved faithfully with an N-particle orthonormal basis measurement and only N bits of classical information.

Quantum Discord Dynamics of Three Qubits in Non-Markovian Environments

We investigate the dynamics of pairwise quantum discord (QD) for a mixed three-qubit W-type state in three independent non-Markovian reservoirs at zero temperature, each of which is modeled by a leaky cavity with Lorentzian spectral density. The influence of the environments amount of non-Markovianity, the detuning between the qubit frequency and the cavity centre frequency, and the purity of the initial state on the QD dynamics are analyzed in detail. It is found that in the non-Markovian regime the system-reservoir interactions induce QD revivals and oscillations no matter whether the detuning is zero or not. Moreover, QD can be preserved for a long time if the non-Markovian condition and the detuning condition are satisfied simultaneously.

The Vacuum of Lattice Gauge Theory with Fermions and Spontaneous Chiral Symmetry Breaking

The vacuum structure of lattice gauge theory with fermions is studied by the variational method. The fermion condensate is given as a function of .

Unitary Transformations in Lattice Gauge Theory with Fermions and the Meson Spectrum

The Hamiltonian of lattice gauge theory with fermions is diagonalized in the one-link approximation and the meson spectrum of SU(N) theory with one flavor is derived.

The exact ground state of a Hamiltonian lattice gauge theory

A modified Hamiltonian of lattice gauge theory including 2-plaquette interaction has been studied. We have found the exact ground state of the theory.

Independent Plaquette Trial Action for 4-Dimensional Lattice Gauge Theory

Based on the explicit expressions of the plaquette formulations, the independent plaquette trial action for 4-dimensional lattice gauge theory is introduced. As an example, the mean plaquette energy for the lattice gauge theory is calculated by using action variational approach with the independent trial action. The results are in good agreement with the Monte Carlo results in the strong coupling and the crossover region, and the curve is smooth in the whole region, which show that 4-dimensional theory has only a single, confining phase. The unwanted discontinuity of given by the single link trial action, which is used in the earlier variational calculations has been avoided.

Phase Transition in Two-Dimensional Josephson-Junction Arrays*

The self-charging model of two-dimensional Josephson-junction arrays at is studied by the coupled cluster expansion method. The calculated results for the mass gap converge nicely. Besides the critical point, we also determine the critical parameters at . The system displays a second-order phase transition and the results are consistent with those obtained by other methods.

The Improved Hamiltonian and ρ-ω Mass Difference in Lattice Gauge Theory*

We formulate a Hamiltonian theory on the lattice including next-to-nearest neighbor fermion interactions. A canonical transformation is made to induce a momentum-dependent mass term. The meson spectrum is studied by using this Hamiltonian. The current algebra formula for the pion mass is derived. The ρ-ω mass ratio in the intermediate coupling region is in agreement with the experimental value.

The Decay ρ→ππ in Lattice Gauge Theory*

The hadronic decays are studied by using an improved Hamiltonian including 2-link interactions. We find that the formulation is effective for studying hadronic decays as well as mass spectrum. In the intermediate coupling region, the decay width of ρ meson is found to be of the right order of magnitude.

The mass gap in 2+1 dimensional U(1) lattice gauge theory

We present a variational calculation of the mass gap in 2+1 dimensional U(1) lattice gauge theory using a hamiltonian of which the ground state is exactly known. An exponentially decreasing curve for ma vs 1/g2 is obtained, but the slope is much larger than that predicted in the periodic Gaussian model.