论文标题
量子环境纠缠产生和旋转回声
Qubit-environment entanglement generation and the spin echo
论文作者
论文摘要
我们分析了Qubit-Encrignment纠缠之间的关系，这些纠缠在量子的纯粹dephasing和自旋回声协议的有效性期间可以产生。我们在这里专注于环境的混合状态。我们表明，尽管ECHO协议显然可以抵消经典的环境噪声，但它也可以撤销与Qubit-Encriendment纠缠相关的逐渐变化，并且在这两种情况下，其效率没有明显的差异。此外，我们表明，即使在量子位上局部操作时不存在时，也可以在回声协议的末尾生成Qubit-Encrignment纠缠。我们证明，这只能在回声协议持续时间进行微调后才发生在孤立的时间点。最后，我们讨论了回声信号的特定特征的观察条件，可以作为联合环境演变的纠缠性质的见证。
We analyze the relationship between qubit-environment entanglement that can be created during the pure dephasing of the qubit and the effectiveness of the spin echo protocol. We focus here on mixed states of the environment. We show that while the echo protocol can obviously counteract classical environmental noise, it can also undo dephasing associated with qubit-environment entanglement, and there is no obvious difference in its efficiency in these two cases. Additionally, we show that qubit-environment entanglement can be generated at the end of the echo protocol even when it is absent at the time of application of the local operation on the qubit (the π pulse). We prove that this can occur only at isolated points in time, after fine-tuning of the echo protocol duration. Finally, we discuss the conditions under which the observation of specific features of the echo signal can serve as a witness of the entangling nature of the joint qubit-environment evolution.
