通过对开放量子系统的连续监测，研究了实际探测器中的缺陷对量子态和参数估计问题的影响。具体地说，我们重新研究了由Gambetta和Wiseman [Phys.Rev.A64，042105（2001）]引入的具有未知拉比频率的二能级原子系统。我们只考虑直接光电探测，并使用Warszawski，Wiseman和Mabuchi [Phys. Rev. A 65，023802（2002）]报道的现实量子轨道理论。最显著的影响来自有限带宽，对应于光电二极管响应时间的不确定性。除非带宽明显大于拉比频率，否则观测者获取未知拉比频率和原子状态信息的能力将受到严重损害。这一结果对现实探测器存在未知参数时的量子控制有影响，甚至对理想探测器也有影响，因为它意味着测量记录中的大部分信息都包含在探测的精确定时中。
英文摘要：
We investigate the effect of imperfections in realistic detectors upon the problem of quantum state and parameter estimation by continuous monitoring of an open quantum system. Specifically, we have reexamined the system of a two-level atom with an unknown Rabi frequency introduced by Gambetta and Wiseman [Phys. Rev. A 64, 042105 (2001)]. We consider only direct photodetection and use the realistic quantum trajectory theory reported by Warszawski, Wiseman, and Mabuchi [Phys. Rev. A 65, 023802 (2002)]. The most significant effect comes from a finite bandwidth, corresponding to an uncertainty in the response time of the photodiode. Unless the bandwidth is significantly greater than the Rabi frequency, the observer's ability to obtain information about the unknown Rabi frequency, and about the state of the atom, is severely compromised. This result has implications for quantum control in the presence of unknown parameters for realistic detectors, and even for ideal detectors, as it implies that most of the information in the measurement record is contained in the precise timing of the detections.
[Dissertation] Fundamental Limits to Single-Photon Detection
量子力学巩固了光的性质与光的探测之间的密切关系。从历史上看，光电探测的量子理论一般分为两类：第一类试图确定当检测到光电子时测量的是什么量子场，为光电探测奠定了理论基础。第二类是唯象理论，它们非常小心地对特定光电探测器的细节进行建模。在这篇论文中，我们填补了这两个模型之间的差距，在现代文献中的光电探测，通过构建一个完全量子力学和足够现实的模型，包括所有阶段的光电探测过程：传输，放大，和最后的经典测量。我们在量子信息理论的框架内使用正算子值测度（POVM）的语言来实现这一点。本论文包含以前发表在三篇论文的材料：Propp，Tz。B & van Enk，S. J.（2019年）。非线性放大：光子计数的量子极限改进。Optics Express 27，16，23454-23463。Propp，Tz. B & van Enk，S. J.（2019年）。单光子探测的量子网络。物理评论A，100，033836。Propp，Tz. B & van Enk，S. J.（2020）。如何投射到任意的单光子波包上。物理评论A，102，053707。
Unlocking photodetection for quantum sensing with Bayesian likelihood-free methods and deep learning
Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）；Quantum Innovation Centre (Q.InC), Agency for Science Technology and Research (A*STAR)（量子创新中心（Q.InC），科学技术研究局（A*STAR））；Qilimanjaro Quantum Tech（Qilimanjaro量子技术）
Analytic properties of cross-click operators in passive multi-basis photodetection: monotonicity, exact convergence rates, and dimension reduction for quantum key distribution
A complete quantum process model for physically realistic photo-detection in the joint photon-number and spectral degrees of freedom
School of Natural Sciences, National University of Sciences and Technology（国立科技大学自然科学学院）；Department of Physics, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences（拉合尔管理科学大学赛义德巴巴尔·阿里科学与工程系物理系）；National Centre for Physics (NCP)（国家物理中心）
Sharjah Maritime Academy（沙迦海事学院）；Indian Institute of Technology Jodhpur（印度理工学院乔德普尔分校）；University of the Basque Country UPV/EHU（巴斯克大学）；IKERBASQUE, Basque Foundation for Science（伊卡巴萨奎，巴斯克科学基金会）；EHU Quantum Center（EHU量子中心）
