论文标题
存在噪声的量子幅度估计
Quantum Amplitude Estimation in the Presence of Noise
论文作者
论文摘要
量子振幅估计(QAE) - 一种技术,可以用比标准采样量估计给定量子状态的幅度较少的问题 - 是几种重要的量子算法中的一个关键子仪,包括Grover搜索和量子Monte-Carlo方法。在近期嘈杂的中间量子量子(NISQ)设备中实施QAE的障碍是需要执行量子相估计(QPE)(QPE)(一种昂贵的程序)作为子例程。 QAE的各种无QPE方法取消了这种障碍,其中谷格对不同深度 /力量的疑问(通常按照“时间表”)立即进行测量和经典的后后处理技术,例如最大的可能性估计(MLE)。关于这些无QPE QAE方案中各种查询时间表的最佳性的现有分析,迄今为止假定没有噪声的系统。在这项工作中,我们在常见的噪声模型下分析了无QPE QAE,这些噪声模型可能会折磨NISQ设备,并报告嘈杂制度中各种查询时间表的最佳性。我们证明,鉴于对系统的准确噪声表征,必须选择一个时间表,以平衡更高深度电路实现的更大理想性能与噪声引起的误差相应更大的积累之间的权衡。
Quantum Amplitude Estimation (QAE) -- a technique by which the amplitude of a given quantum state can be estimated with quadratically fewer queries than by standard sampling -- is a key sub-routine in several important quantum algorithms, including Grover search and Quantum Monte-Carlo methods. An obstacle to implementing QAE in near-term noisy intermediate-scale quantum (NISQ) devices has been the need to perform Quantum Phase Estimation (QPE) -- a costly procedure -- as a sub-routine. This impediment was lifted with various QPE-free methods of QAE, wherein Grover queries of varying depths / powers (often according to a "schedule") are followed immediately by measurements and classical post-processing techniques like maximum likelihood estimation (MLE). Existing analyses as to the optimality of various query schedules in these QPE-free QAE schemes have hitherto assumed noise-free systems. In this work, we analyse QPE-free QAE under common noise models that may afflict NISQ devices and report on the optimality of various query schedules in the noisy regime. We demonstrate that, given an accurate noise characterization of one's system, one must choose a schedule that balances the trade-off between the greater ideal performance achieved by higher-depth circuits, and the correspondingly greater accumulation of noise-induced error.