Jeffers John, Oi Daniel K L, Brougham Thomas
Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG, UK.
Philos Trans A Math Phys Eng Sci. 2024 Dec 30;382(2287):20230338. doi: 10.1098/rsta.2023.0338. Epub 2024 Dec 24.
Quantum retrodiction, in which the state of a quantum system prior to a measurement is assigned based on the results of that measurement, has had a long history and has been used in quantum optics research for decades. Here we summarize the theory and point out some of the more interesting results, before applying the theory to state identification from multiple shots of an experiment. One surprising result is that we show that a photodetector with low quantum efficiency can discriminate between photonic states better than a detector with a higher efficiency.This article is part of the theme issue 'The quantum theory of light'.
量子反推，即根据测量结果来确定量子系统在测量之前的状态，有着悠久的历史，并且在量子光学研究中已被使用了数十年。在此，我们总结该理论并指出一些更有趣的结果，然后将该理论应用于从多次实验测量中进行状态识别。一个令人惊讶的结果是，我们发现量子效率低的光电探测器比效率高的探测器能更好地区分光子态。本文是主题为“光的量子理论”的特刊的一部分。
