Linux下某型制导弹目标跟踪并行算法

针对某型电视制导弹的图像特点,在Linux平台上设计了一种并行算法用于完成目标跟踪。算法思想:将制导弹的目标跟踪任务划分为图像采集、纠旋、显示和目标跟踪,程序中创建两个线程用于完成该任务;其中线程1完成图像采集、纠旋和显示;线程2完成目标跟踪。实验表明该算法实现了Linux环境下图像的实时采集、纠旋、显示和目标跟踪,与Windows下的目标跟踪算法相比,该算法有效的节省了资源。

Entanglement of Three Atoms Induced by a Coherent Field

We calculate the concurrence and spin squeezing parameter of three atoms induced by a coherent field. It shows that when the mean numbers of photon of the field is very small, concurrence exhibits a certain kind of approximative periodic vibration. With the increase of the mean numbers of photon, its periodicity will be interrupted. As for the relationship between the concurrence and spin squeezing, numeric result shows that under Dick model, spin squeezing serves as a sufficient but not necessary condition for concurrence.

Thermal Entanglement of a Two-Qubit XXZ Heisenberg Chain with Dzialoshinski-Moriya Interaction

The effect of DziaJoshinski-Moriya （DM） interaction on thermal entanglement of a two-qubit XXZ spin chain in a homogenous magnetic field is investigated. It is found that the DM interaction can enhance thermal entanglement. When D is large enough, the entanglement can exist for larger temperatures and strong magnetic field.

Entanglement and Fidelity of a Spin Ladder with Dzyaloshinsky-Moriya Interaction

The spin ladder with Dzyaloshinsky-Moriya interaction is investigated by using the quantum renormalization-group method.The entanglement and fidelity are periodic functions of the time and oscillate between zero and one.The oscillation period decreases with either the interaction in the spin ladder or the Dzyaloshinsky-Moriya interaction increasing.When the system relates to the environment,both entanglement and fidelity oscillate with a damping rate related to intrinsic decoherence rate,the interaction in the spin ladder,and the Dzyaloshinsky-Moriya interaction.

Thermal Entanglement of an XY Two-Qutrit Spin Chain with Dzialoshinski—Moriya Interaction

The effect of Dzialoshinski-Moriya(DM)interaction on thermal entanglement of an XY two-qutrit spinchain is investigated.We find that DM interaction and the anisotropy parameter can enhance quantum thermal entanglementto a maximal value individually.However,when both of them take large values,the entanglement is notenhanced,but is destroyed.Our analysis will shed some light on the understanding of the effect of the DM interactionon thermal entanglement of an XY two-qutrit spin chain.

Multipartite Entanglement Transfer from Multi-Mode Coherent State to Spin Qubits

The multipartite entanglement transfer from continuous variable system to spin qubits is investigated. We select multi-mode coherent field as continuous variable field. It is found that the qubits can not gain tripartite entanglement for states of close to GHZ state from the multi-mode coherent field. Moreover, the ability of the qubits gain the tripartite entanglement for states close to W state and bipartite entanglement from the continuous variable system is depended on the phase of multi-mode coherent field.

Entanglement Resonance of End Spins in Different Spin Chains

The entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with external magnetic field. When the modulation frequency equals twice of the magnetic field, the entanglement resonance is larger than that at other modulation frequencies and decreases as the number of spins in the chain increases. When the modulation frequency equals the magnetic field, the entanglement resonance can be reduced to a quite low value by varying the coupling along z axis.

Degree of Entanglement and Violation of Bell Inequality by Two-Spin-1/2 States

Bell inequality is violated by the quantum mechanical predictions made from an entangled state of the composite system. In this paper we examine this inequality and entanglement measures in the construction of the coherent states for two-qubit pure and mixed states, we find a link to some entanglement measures through some new parameters （amplitudes of coherent states）. Conditions for maximal entanglement and separability are then established for both pure and mixed states. Finally, we analyze and compare the violation of Bell inequality for a class of mixed states with the degree of entanglement by applying the formalism of Horodecki et al.

Entanglement Entropy Signature of Quantum Phase Transitions in a Multiple Spin Interactions Model

Through the Jordan Wigner transformation, the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of Green＇s function theory. In the absence of four-spin interactions, the ground state presents plentiful quantum phases due to the multiple spin interactions and magnetic fields. It is shown that the two-site entanglement entropy is a good indicator of quantum phase transition （QPT）. In addition, the alternating interactions can destroy the magnetization plateau and wash out the spin-gap of low-lying excitations. However, in the presence of four-spin interactions, apart from the second order QPTs, the system manifests the first order OPT at the tricritical point and an additional new phase called ＂spin waves＂, which is due to the collapse of the continuous tower-like low-lying excitations modulated by the four-spin interactions for large three-spin couplings.

Phase State as a Limiting Case of SU(1,1) Coherent State

We show that the Susskind-Glogower phase state is a limiting case of a kind of SU（1,1） coherent states. By analogy, based on the bipartite entangled state representation （ESR） we demonstrate that an appropriate SU（1,1） coherent state composed of the two-mode unitary phase operator e^i also leads to a new phase state in two-mode Fock space, e^i is diagonalized in the ESR.

Quantum Communication in Spin Chain with Multiple Spin Exchange Interaction

The transmission of quantum states in the anisotropic Heisenberg XXZ chain model with three-spin exchange interaction is studied. The average fidelity is used to evaluate the state transfer. It is found that quantum communication can be enhanced by the anisotropic coupling and multiple spin interaction. Such spin model can reduce the time required for the perfect state transmission where the fidelity is unity. The maximally entangled Bell states can be generated and separated from the whole quantum systems.

Entanglement Dynamics of Multipartite Systems Under Decoherence from a Spin Environment

The entanglement evolution of multipartite quantum states under a spin environment is analyzed. Due to interaction, the extent to which the entanglement vanishes depends not only on the size of system and the structure of quantum states, but also on the exchange couplings with environment. The decoherence-free subspaces have been identified by using the linear entropy.

Energy as Entanglement Witness in Bilinear-Biquadratic Spin-1 Chain

Energy is introduced as an entanglement witness to describe the entanglement property of a quantum system. The thermal equilibrium system is guaranteed to be entangled when system is cooled down below the entanglement temperature TE. By virtue of this concept we exploit the minimum separable state energy and entanglement temperature TE of the bilinear-biquadratic antiferromagnetic spin-1 chain model. We numerically calculate TE for arbitrary values of the strength of biquadratic exchange interaction Q up to N=7. We find TE decreases with Q for fixed N when Q is between -3 and 1/3 （J = 1）. In this regime TE also decreases with N for fixed Q and varies slowly for large N. While the thermal system is always entangled when Q is smaller than -3.

Effects of Different Spin-Spin Couplings and Magnetic Fields on Thermal Entanglement in Heisenberg XYZ Chain

The effects of spin-spin interaction on thermed entanglement of a two-qubit Heisenberg XYZ model with different inhomogeneous magnetic fields are investigated. It is shown that the entanglement is dependent on the spin-spin interaction and the inhomogeneous magnetic fields. The larger the Ji （i-axis spin-spin interaction）, the higher critical value the Bi （i-axis uniform magnetic field） has. Moreover, in the weak-field regime, the larger Ji corresponds to more entanglement, while in the strong-field regime, different Ji correspond to the same entanglement. In addition, it is found that with the increase of Ji, the concurrence can approach the maximum value more rapidly for the smaller Bi, and can reach a larger value for the smaller bi （i-axis nonuniform magnetic field）. So we can get more entanglement by increasing the spin-spin interaction Ji, or by decreasing the uniform magnetic field Bi and the nonuniform magnetic field hi.

Complete entanglement analysis on electron spins using quantum dot and microcavity coupled system

We present an entanglement analysis protocol on entangled electron spins using quantum dot(QD)and microcavity coupled system.Each quantum dot is placed in the microcavity and ancilla photon input-output process could be used to check the parity of the quantum dots.After the parity check process,the user only needs to measure the spin direction of the QD spin,and the state information can be readout completely.The feasibility of our scheme and the experimental challenge are discussed by considering currently available techniques.

Entanglement in a two-spin (1/2,3/2) mixed-spin Heisenberg XX chain with an inhomogeneous external magnetic field

By using the concept of negativity, we investigate the thermal entanglement of a two-spin (1/2, 3/2) mixed-spin Heisenberg XX chain with an inhomogeneous external magnetic field. We obtain the analytical results of entanglement of this model. For the case of uniform magnetic field, we find that the critical temperature is higher than the results of the spin-1/2 chain and (1/2,1) mixed-spin chain. And by adjusting the nonuniform parameter b, one is able to obtain more entanglement at a higher temperature.

Effect of decoherence from a spin environment on the entanglement dynamics of two-qutrit states

The entanglement dynamics of a two-qutrit system under decoherence from a spin environment is investigated by using negativityas entanglement measure. Our results imply that the entanglement evolution depends not only on the coupling strength and thetunneling elements of the environment but also on the number of the freedom degrees and the initial state of the environment.

Thermal Entanglement in Two-Qutrit Heisenberg XX Chain with Different Dzyaloshinskii-Moriya Interaction and Nonuniform Magnetic Field

The effects of the different Dzyaloshinskii-Moriya （DM） interaction on thermal entanglement of a two-qutrit Heisenberg XX spin chain in a nonuniform magnetic field are investigated. Our results imply that the x-component DM interaztion plays a central role in enhancing quantum entanglement and it has a higher critical temperature than the z-component DM interaction. The entanglement can be tunable controlled by changing the multiple of the magnetic fields B1 and B2. Also we found that different DM interaction are competitive to each other in some conditions.

Effects of noisy quantum channels on one-qubit rotation gate

We investigate the effects of noisy quantum channels on the entanglement of cluster states and one way quantum computational gates.We take a basic model,the rotational gate about x axis based on the cluster state,in order to get the most essential effects of the paradigmatic noisy quantum channels.The entanglement of cluster states in the noisy channels and the fidelity between the rotated state without noisy channel and that with noisy channel are calculated.

Thermal Spin Squeezing as a Signature of Thermal Global Entanglement in Heisenberg Models

We study thermal spin squeezing (TSS) and thermal global entanglement (TGE) in a general Heisenberg spin chain, in the presence of Dzyaloshinskii-Moriya interaction and an external magnetic field. We derive an inequality associating the squeezing parameter and the global concurrence, which establishes (TSS) as a signature of (TGE). The inequality reduces to equality for particular symmetric chains which also associates TSS with bipartite entanglement in such systems. We also check the results by presenting two numerical examples.