研究了一个处在均匀外磁场中的包含四个量子比特的各向同性海森堡XY模型中,两个间隔的量子比特之间的量子热纠缠,并用并发度来量度.这个模型包含两种量子比特:自旋为1/2的量子比特和自旋为S的量子比特.结果表明,外磁场可以引起两个间隔的量子比特之间的量子热纠缠.热纠缠的幅度与自旋S,温度T以及均匀外磁场B有关.因此,可以通过调节B的取值来控制热纠缠.当S足够大时,阈值温度也可能很高.这个特性可以被用于研究凝聚态系统的热纠缠,并且在固体系统进行量子信息研究中也将发挥很大的作用.
Quantum thermal entanglement of two next nearest-neighbor qubits in a four-qubit isotropic Heisenberg XY model consisting of spin 1/2 and spin S in a homogeneous external magnetic field B was investigated by concurrence measure of entanglement.The results show that the external magnetic field can induce the thermal entanglement of two next nearest-neighbor qubits.The amplitude of thermal entanglement is dependent on the spin S,temperature T and homogeneous external magnetic field B.As a result,it is feasible to control thermal entanglement by adjusting the value of external magnetic field B.When S is sufficiently large,the threshold temperature above which there is no thermal entanglement may also be very high.The feature Can be used in high-temperature entanglement of condensed matter systems and it will be useful in the research of quantum information in solid systems.
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