论文标题
量子重置的基本界限
Fundamental Bounds on Qubit Reset
论文作者
论文摘要
量子重置是需要熵导出的操作量子设备的基本先决条件。通过将量子耦合到ancilla的需求，可以获得重置量子的最快，最准确的方法。在这里，我们以最大的忠诚度和最小时间来得出量子重置的基本界限，假设控制量子量，并且无法控制对附件。使用Qubit的Lie代数的Cartan分解加上两级Ancilla，我们确定了可以纯化量子的相互作用和对照的类型。对于这些配置，我们表明，时间优势的协议包括量子和Ancilla之间的纯度交换，在所有情况下，最大忠诚度相同，但最小时间取决于相互作用和控制的类型。此外，我们发现随着Ancilla Hilbert空间的大小，最大可实现的保真度增加，而重置时间保持恒定。
Qubit reset is a basic prerequisite for operating quantum devices, requiring the export of entropy. The fastest and most accurate way to reset a qubit is obtained by coupling the qubit to an ancilla on demand. Here, we derive fundamental bounds on qubit reset in terms of maximum fidelity and minimum time, assuming control over the qubit and no control over the ancilla. Using the Cartan decomposition of the Lie algebra of qubit plus two-level ancilla, we identify the types of interaction and controls for which the qubit can be purified. For these configurations, we show that a time-optimal protocol consists of purity exchange between qubit and ancilla brought into resonance, where the maximum fidelity is identical for all cases but the minimum time depends on the type of interaction and control. Furthermore, we find the maximally achievable fidelity to increase with the size of the ancilla Hilbert space, whereas the reset time remains constant.
