近日，美国麻省理工学院的Junxin Chen及其研究团队取得一项新进展。经过不懈努力，他们对因果状态估计和海森堡测不准原理进行研究。相关研究成果已于2024年8月5日在国际知名学术期刊《物理评论A》上发表。
在本文中，研究人员证明了一个事实——无论是否存在系统的反馈控制，无论测量记录是在反馈环内部还是外部被访问，都无需假设马尔可夫动力学或高斯噪声。事实上，使用环内测量记录的因果估计器与使用环外测量记录的因果估计器一样精确。这些结果阐明了因果估计器对非马尔可夫量子系统的作用，厘清了其在估计和控制中对于环内和环外测量的同等重要性，并简化了未来基于测量的量子反馈控制的实验。
据悉，通过对连续测量记录进行适当的滤波，可以估计出含噪量子系统的可观测量。这种滤波对于状态估计具有重要意义，如果滤波器是因果的，那么它对于基于测量的反馈控制也具有重要意义。因此，一对因果估计的共轭可观测量必须满足海森堡不确定性原理。
附：英文原文
Title: Causal state estimation and the Heisenberg uncertainty principle
Author: Junxin Chen, Benjamin B. Lane, Su Direkci, Dhruva Ganapathy, Xinghui Yin, Nergis Mavalvala, Yanbei Chen, Vivishek Sudhir
Issue&Volume: 2024/08/05
Abstract: The observables of a noisy quantum system can be estimated by appropriately filtering the records of their continuous measurement. Such filtering is relevant for state estimation, and if the filter is causal, also relevant for measurement-based feedback control. It is therefore imperative that a pair of conjugate observables estimated causally satisfy the Heisenberg uncertainty principle. In this article, we prove this fact—without assuming Markovian dynamics or Gaussian noises, in the presence or absence of feedback control of the system, and where in the feedback loop (inside or outside) the measurement record is accessed. Indeed, causal estimators using the in-loop measurement record can be as precise as those using the out-of-loop record. These results clarify the role of causal estimators to non-Markovian quantum systems, restore the equanimity of in-loop and out-of-loop measurements in their estimation and control, and simplify future experiments on measurement-based quantum feedback control.
DOI: 10.1103/PhysRevA.110.022207
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.022207
期刊信息
Physical Review A：《物理评论A》，创刊于1970年。隶属于美国物理学会，最新IF：2.97
官方网址：https://journals.aps.org/pra/
投稿链接：https://authors.aps.org/Submissions/login/new