Sun Yifan, Zhang Jun-Yi, Wu Lian-Ao
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.
Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), PO Box 644, 48080, Bilbao, Spain.
Sci Rep. 2019 Jul 30;9(1):11035. doi: 10.1038/s41598-019-47479-9.
Leakage errors damage a qubit by coupling it to other levels. Over the years, several theoretical approaches to dealing with such errors have been developed based on perturbation arguments. Here we propose a different strategy: we use a sequence of finite rotation gates to exactly eliminate leakage errors. The strategy is illustrated by the recently proposed charge quadrupole qubit in a triple quantum dot, where there are two logical states to encode the qubit and one leakage state. We found an su(2) subalgebra in the three-level system, and by using the subalgebra we show that ideal Pauli x and z rotations, which are universal for single-qubit gates, can be generated by two or three propagators. In addition, the magnitude of detuning fluctuation can be estimated based on the exact solution.
泄漏误差通过将量子比特耦合到其他能级来破坏它。多年来，基于微扰论证已经开发了几种处理此类误差的理论方法。在这里，我们提出一种不同的策略：我们使用一系列有限旋转门来精确消除泄漏误差。最近在三量子点中提出的电荷四极量子比特说明了该策略，其中有两个逻辑态来编码量子比特和一个泄漏态。我们在三能级系统中发现了一个(su(2))子代数，并且通过使用该子代数我们表明，对于单量子比特门通用的理想泡利(x)和(z)旋转可以由两个或三个传播子生成。此外，可以基于精确解来估计失谐波动的大小。
