相移控制下XX自旋链中的量子态传递

研究了由Aharonov-Casher相互作用产生的相移对XX自旋链中量子态传递的影响。对信道的纠缠度及传递量子态的保真度进行数值模拟后发现，控制相移的方法可以有效抵抗信道的消相干作用，显著提高自旋链中量子比特间的纠缠度及量子态的保真度。此外，量子态发送端与接收端之间相对位置的不同也会影响纠缠度和保真度的大小，在包含偶数个自旋格点的环形自旋链中，当发送端与接收端处在直径上相对的位置时，接收端的纠缠度和量子态传递的保真度可以达到最大值。

Quantum state transfer in XX spin chain with phase shift control

The effect of phase shift generated by Aharonov-Casher interaction on the quantum state transfer in a XX spin chain is investigated. The concurrence of the channel and the fidelity of the state are calculated by numerical simulations. It is found that by controlling the phase shift, decoherence is suppressed, and the entanglement and fidelity can be enhanced. In addition, the relative positions between the sender and the receiver have an influence on the entanglement and fidelity. When they are located at diametrically opposite sites in an even spin ring respectively, the maximum values of entanglement and fidelity can be obtained.