Quantum state tomography is a powerful, but resource-intensive, general solution for numerous quantum information processing tasks. This motivates the design of robust tomography procedures that use relevant resources as sparingly as possible. Important cost factors include the number of state copies and measurement settings, as well as classical postprocessing time and memory. In this work, we present and analyze an online tomography algorithm designed to optimize all the aforementioned resources at the cost of a worse dependence on accuracy. The protocol is the first to give provably optimal performance in terms of rank and dimension for state copies, measurement settings and memory. Classical runtime is also reduced substantially and numerical experiments demonstrate a favorable comparison with other state-of-the-art techniques. Further improvements are possible by executing the algorithm on a quantum computer, giving a quantum speedup for quantum state tomography.

翻译：量子信息处理任务中,量子状态断层扫描是一种强大但资源密集的通用解决方案。 这促使设计了强有力的断层扫描程序,尽可能少地使用相关资源。 重要的成本因素包括国家复制件和测量设置的数量,以及古典后处理时间和记忆。 在这项工作中,我们提出并分析了一种在线断层扫描算法,目的是优化所有上述资源,而费用更低地依赖准确性。 协议是第一个为国家复制品、测量设置和记忆在级别和范围方面提供可辨称最佳的性能的协议。 经典运行时间也大大缩短,数字实验显示了与其他最新技术的有利比较。 通过对量子计算机进行算法,为量子状态断层扫描提供量子速度,可以进一步改进。