【作者】 唐煌；

【导师】 方建兴；

【作者基本信息】 苏州大学 ， 光学， 2006， 硕士

【摘要】 本文通过研究纯态信道中的量子隐形传态，进而研究海森堡热纠缠信道中的量子隐形传态。主要讨论了基于海森堡XX相互作用且处于热环境下的二量子比特的量子纠缠，以及以此纠缠为量子通道，对均匀分布在单位球面上单量子态进行量子隐形传态，同时详细讨论了在两个海森堡热纠缠信道中，一对量子纠缠态的隐形传送，分别分析了外界环境(温度T和磁场B)对热纠缠及量子隐形传态的影响，求出非零热纠缠度及保真度大于2／3的临界温度。同时发现，在海森堡热纠缠信道中，由于各种信道在混合信道中的权重不同，会得到不同的测量结果，我们一般选择权重系数最大时的测量结果进行分析。 通过具体的计算，我们发现在二量子比特海森堡XX模型中，保真度大于2／3的外界条件要比产生非零的纠缠度C所需的外界条件复杂。同时还发现产生热纠缠的临界温度T_c(J)与外界磁场没有关系，而实现量子隐形传递的临界温度T_f(B，J)与外界磁场有关系。当增加磁场时，产生非零热纠缠的条件范围在变大，但是，却不利于热纠缠信道中的隐形传送。可以这样认为，纠缠度C仅仅描述了热纠缠的一个方面，但不能表明在热纠缠信道中隐形传递的质量如何，这就需要保真度f来描述。通过两种情形的研究，我们均发现，当磁场B较弱，温度T很低的时候，以海森堡热纠缠混合态作为量子信道的隐形传递要优越于经典信道。更多还原

【Abstract】 This thesis investigates the basis theory of teleportation in pure channels firstly, then the teleportation in thermally entangled channels is also analyzed. In this paper, we mainly study quantum entanglement in Heisenberg XX model, with that, the quantum teleportation via Heisenberg thermally entangled state is studied. At the same time, entanglement teleportation, using thermally entangled state of two two-qubit Heisenberg XX chain as resource, with nonzero thermal entanglement and fidelity better than any classical communication protocol is possible. And then, the influence about entanglement and teleportation due to the effects of environment (temperature T and magnetic field B), is analyzed respectively, we figure out the critical temperature when the concurrence is zero and the fidelity is 2/3. It is found that, in Heisenberg thermally entangled channels, we will get different result with different weight term of each channel, we analyze the course with the largest weight term.As the whole, it is found that, in Heisenberg XX model, the condition for the thermally quantum channel to teleport states with fidelity strictly greater than 2/3 is expectedly stronger than that for thermal concurrence to be nonzero. In addition, the critical temperature is independent on the magnetic field B when the concurrence is zero, and the critical temperature is dependent on the magnetic field B when the fidelity is 2/3. It is also found that with increasing magnetic field B we have an increasing range of nonzero thermal entanglement which is, however, not suitable for quantum teleportation. Therefore, the thermal concurrence only describes certain aspects of the thermal entanglement. In particular, it does not indicate the quality of thermal entanglement for quantum更多还原