Quantum phase estimation is an important component in diverse quantum algorithms. However, it suffers from spectral leakage, when the reciprocal of the record length is not an integer multiple of the unknown phase, which incurs an accuracy degradation. For the existing single-sample estimation scheme, window-based methods have been proposed for spectral leakage mitigation. As a further advance, we propose a dual-frequency estimator, which asymptotically approaches the Cramer-Rao bound, when multiple samples are available. Numerical results show that the proposed estimator outperforms the existing window-based methods, when the number of samples is sufficiently high.

翻译：量子阶段估算是各种量子算法的一个重要组成部分,但受光谱渗漏的影响,因为记录长度的对等并非未知阶段的整数倍,导致准确性降解。对于现有的单一抽样估算办法,提出了减少光谱渗漏的基于窗口的方法。作为进一步的进展,我们提出了一个双频测算器,当有多个样本时,该测算器会不时接近Cramer-Rao约束区。数值结果显示,在样品数量足够多的情况下,拟议的测算器超过了现有基于窗口的方法。