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Guo-Feng Zhang

Publications and source records attributed to Guo-Feng Zhang.

62 records · Page 4Linked to original sources
arXiv2008

Berry Phase in a Two-atom Jaynes-Cummings Model with Kerr Medium

he Jaynes-Cummings model (JCM) is an very important model for describing interaction between quantized electromagnetic fields and atoms in cavity quantum electrodynamics (QED). This model is generalized in many different direction since it predicts many novel quantum effects that can be verified by modern physics experimental technologies. In this paper, the Berry phase and entropy of the ground state for arbitrary photon number $n$ of a two-atom Jaynes-Cummings model with Kerr like medium are investigated. It is found that there are some correspondence between their images, especially the existence of a curve in the $Δ-\varepsilon$ plane along which the energy, Berry phase and entropy all reach their special values. So it is available for detecting entanglement by applying Berry phase.

quant-ph↗
arXiv2008

Mutual information and swap operation in the two-qubit Heisenberg model with Dzyaloshinskii-Moriya anisotropic antisymmetric interaction

Mutual information and swap operation in the two-qubit Heisenberg model with the Dzyaloshinskii-Moriya (DM) anisotropic antisymmetric interaction are investigated. It is found that the mutual information I of such a quantum channel is sensitive to the initial conditions and declines with the increase of the temperature. The DM interaction can lead to a higher mutual information, especially for the ferromagnetic case. The entanglement quality of input states cannot enhance the mutual information of the quantum channel. When the DM interaction is large, the mutual information will be the maximum value 2 for a non-entangled input state, but it is 1 for a maximally entangled input one. It is also shown that the swap operation can be implemented for some kinds of DM coupling. The conditions of the DM coupling under which the swap operation is feasible are established.

quant-ph↗
arXiv2008

Geometric phase of a bipartite system with Dzyaloshinski-Moriya interaction

The Berry phase of a bipartite system described by a Heisenberg XXZ model driven by a one-site magnetic field is investigated. The effect of the Dzyaloshinski-Moriya (DM) anisotropic interaction on the Berry phase is discussed. It is found that the DM interaction affects the Berry phase monotonously, and can also cause sudden change of the Berry phase for some weak magnetic field cases.

quant-ph↗
arXiv2008

Entangled quantum heat engines based on two two-spin systems with Dzyaloshinski-Moriya anisotropic antisymmetric interaction

We construct an entangled quantum heat engine (EQHE) based on two two-spin systems with Dzyaloshinski-Moriya (DM) anisotropic antisymmetric interaction. By applying the explanations of heat transferred and work performed at the quantum level in Kieu's work [PRL, 93, 140403 (2004)], the basic thermodynamic quantities, i.e., heat transferred, net work done in a cycle and efficiency of EQHE are investigated in terms of DM interaction and concurrence. The validity of the second law of thermodynamics is confirmed in the entangled system. It is found that there is a same efficiency for both antiferromagnetic and ferromagnetic cases, and the efficiency can be controlled in two manners: 1. only by spin-spin interaction J and DM interaction D; 2. only by the temperature T and concurrence C. In order to obtain a positive net work, we need not entangle all qubits in two two-spin systems and we only require the entanglement between qubits in a two-spin system not be zero. As the ratio of entanglement between qubits in two two-spin systems increases, the efficiency will approach infinitely the classical Carnot one. An interesting phenomenon is an abrupt transition of the efficiency when the entanglements between qubits in two two-spin systems are equal.

quant-ph↗
arXiv2007

Thermal entanglement and teleportation in a two-qubit Heisenberg chain with Dzyaloshinski-Moriya anisotropic antisymmetric interaction

Thermal entanglement of a two-qubit Heisenberg chain in presence of the Dzyaloshinski-Moriya (DM) anisotropic antisymmetric interaction and entanglement teleportation when using two independent Heisenberg chains as quantum channel are investigated. It is found that the DM interaction can excite the entanglement and teleportation fidelity. The output entanglement increases linearly with increasing value of input one, its dependences on the temperature, DM interaction and spin coupling constant are given in detail. Entanglement teleportation will be better realized via antiferromagnetic spin chain when the DM interaction is turned off and the temperature is low. However, the introduction of DM interaction can cause the ferromagnetic spin chain to be a better quantum channel for teleportation. A minimal entanglement of the thermal state in the model is needed to realize the entanglement teleportation regardless of antiferromagnetic or ferromagnetic spin chains.

quant-ph↗
arXiv2005

Thermal entanglement in a two-qubit Heisenberg XXZ spin chain under an inhomogeneous magnetic field

The thermal entanglement in a two-qubit Heisenberg \emph{XXZ} spin chain is investigated under an inhomogeneous magnetic field \emph{b}. We show that the ground-state entanglement is independent of the interaction of \emph{z}-component $J_{z}$. The thermal entanglement at the fixed temperature can be enhanced when $J_{z}$ increases. We strictly show that for any temperature \emph{T} and $J_{z}$ the entanglement is symmetric with respect to zero inhomogeneous magnetic field, and the critical inhomogeneous magnetic field $b_{c}$ is independent of $J_{z}$. The critical magnetic field $B_{c}$ increases with the increasing $|b|$ but the maximum entanglement value that the system can arrive becomes smaller.

quant-ph↗
arXiv2005

Thermal entanglement in a two-spin-qutrit system under a nonuniform external magnetic field

The thermal entanglement in a two-spin-qutrit system with two spins coupled by exchange interaction under a magnetic field in an arbitrary direction is investigated. Negativity, the measurement of entanglement, is calculated. We find that for any temperature the evolvement of negativity is symmetric with respect to magnetic field. The behavior of negativity is presented for four different cases. The results show that for different temperature, different magnetic field give maximum entanglement. Both the parallel and antiparallel magnetic field cases are investigated qualitatively (not quantitatively) in detail, we find that the entanglement may be enhanced under an antiparallel magnetic field.

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