Measuring fluorescence to track a quantum emitter's state: a theory review
Measuring fluorescence to track a quantum emitter's state: a theory review
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DOI：
10.1080/00107514.2020.1747201
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发表时间：
2019-08
影响因子：
2
通讯作者：
P. Lewalle;S. Manikandan;C. Elouard;A. Jordan
中科院分区：
文献类型：
--
作者：
P. Lewalle;S. Manikandan;C. Elouard;A. Jordan
我们回顾了连续监测量子比特通过其自发辐射，在入门级。当代实验已经能够收集腔和传输线中人造原子的荧光，然后测量该发射以获得量子比特状态下的扩散量子轨迹。我们给出了一个简单的理论概述，这样的情况下，使用的框架来自贝叶斯更新概念的克劳斯运营商的基础上，我们适用于这种灵活的框架在常见类型的测量，包括光电探测，零差，外差监测，并说明其等价性的随机主方程形式主义。特别强调的是零差（相敏）监测荧光。我们开发的例子是用来说明量子轨迹的基本方法，但也介绍了一些更先进的当代感兴趣的话题，包括量子测量中的时间箭头，以及从变分原理导出的最佳测量记录的轨迹。我们进行的推导直接从一个简单模型的发展到对最近实验结果的理解。
We review the continuous monitoring of a qubit through its spontaneous emission, at an introductory level. Contemporary experiments have been able to collect the fluorescence of an artificial atom in a cavity and transmission line, and then make measurements of that emission to obtain diffusive quantum trajectories in the qubit's state. We give a straightforward theoretical overview of such scenarios, using a framework based on Kraus operators derived from a Bayesian update concept; we apply this flexible framework across common types of measurements including photodetection, homodyne, and heterodyne monitoring and illustrate its equivalence to the stochastic master equation formalism throughout. Special emphasis is given to homodyne (phase-sensitive) monitoring of fluorescence. The examples we develop are used to illustrate basic methods in quantum trajectories, but also to introduce some more advanced topics of contemporary interest, including the arrow of time in quantum measurement, and trajectories following optimal measurement records derived from a variational principle. The derivations we perform lead directly from the development of a simple model to an understanding of recent experimental results.