发表机构
School of Mathematical Sciences, Fudan University; QICI Quantum Information and Computation Initiative, School of Computing and Data Science, The University of Hong Kong; Shanghai Key Laboratory for Contemporary Applied Mathematics（复旦大学数学科学学院; 香港大学计算与数据科学学院量子信息与计算倡议中心; 当代应用数学上海市重点实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出自适应纠缠辅助Hadamard测试算法，通过迭代细化参考相位实现更强放大，抑制系统性偏差，以设备重启次数为成本度量，在近期量子处理器上高效估计高精度量子相位。
AI 中文摘要
纠缠辅助Hadamard测试（EHT）是一种通过放大相位信号来估计量子相位的实用方法。然而，可行的放大从根本上受限于参考相位的精度，使得该方法在高精度区域效率低下。在这项工作中，我们提出了一种名为自适应纠缠辅助Hadamard测试（AEHT）的算法，该算法迭代地细化参考相位，随着迭代的进行，能够实现逐渐增强的放大。我们进一步考虑了不完美本征态制备的场景，在这种情况下，使用传统EHT估计量子相位时不可避免地存在系统性偏差。这种偏差可以通过所提出的AEHT来抑制。此外，考虑到物理实现，我们采用设备重启次数来衡量量子相位估计的成本，而不是射击次数。数值实验证实了所提出的AEHT在此度量下与传统方法相比的有效性。通过释放大型纠缠态的全部放大能力，这项工作为在近期量子处理器上估计高精度量子相位提供了一种高效方法。
英文摘要
The entanglement-assisted Hadamard test (EHT) is a practical method for estimating a quantum phase by amplifying the phase signal. However, the feasible amplification is fundamentally limited by the accuracy of the reference phase, such that the method is inefficient in the high-precision regime. In this work, we propose an algorithm, called adaptive entanglement-assisted Hadamard test (AEHT), that iteratively refines the reference phase, enabling progressively stronger amplification as the iteration goes by. We further consider the imperfect eigenstate preparation scenario, where a systematic bias is unavoidable when estimating the quantum phase with the conventional EHT. Such a bias can be suppressed by the proposed AEHT. Moreover, taking physical implementation into consideration, we adopt device-restart count to measure the cost of quantum phase estimation, rather than shot count. The numerical experiments confirm the effectiveness of the proposed AEHT compared with conventional methods under this measure. By unlocking the full amplification power of large entangled states, this work offers an efficient method to estimate high-precision quantum phase on near-term quantum processors.
Comments18 pages, 7 figures
