双自旋系统中的量子失协问题研究

Investigation of quantum discord for two-spin system

利用量子失协的几何度量方案研究了双自旋海森伯(Heisenberg)模型中的量子关联特性,得到了一般情形下两量子态量子失协度的解析表达式,讨论了量子位之间的耦合强度、温度和外加磁场强度等对量子关联大小的影响,并给出了对应的量子关联调控方案.此外还发现在低温下量子失协存在突变的现象.结果表明,在双自旋的海森伯模型体系下,可以通过对系统参数(如温度、耦合强度、磁场强度等)的调节来实现对量子关联大小的有效调控,这将会对在量子信息科学中精确控制量子失协和实现量子态的隐形传输以及量子逻辑门的设计提供一定的借鉴和指导意义.

By adopting the concept of the geometric measure of quantum discord, we explore the property ot quantum cor- relation in the two-spin Heisenberg model, gain the analytic expression of quantum discord in the general case, and discuss the influences of the coupling constant, temperature, the intensity of the external magnetic field on magnitude of the quantum correlation. The corresponding scheme of tuning quantum correlation is also given in this paper. In addition, we find that quantum discord has a sudden transition in the lower temperature. Results show that adjusting systematic parameters, which are temperature, coupling strength, magnetic field intensity, etc, is an effective way to control the value of quantum correlation in the double spin Heisenberg model system. This provides a certain reference and significant guidance for the precise control of quantum discord and realizing the teleportation of quantum state and the design of quantum logic gates.