Pokorny Fabian, Zhang Chi, Higgins Gerard, Cabello Adán, Kleinmann Matthias, Hennrich Markus
Department of Physics, Stockholm University, 10691 Stockholm, Sweden.
Departamento de Física Aplicada II, Universidad de Sevilla, E-41012 Sevilla, Spain.
Phys Rev Lett. 2020 Feb 28;124(8):080401. doi: 10.1103/PhysRevLett.124.080401.
The existence of ideal quantum measurements is one of the fundamental predictions of quantum mechanics. In theory, an ideal measurement projects a quantum state onto the eigenbasis of the measurement observable, while preserving coherences between eigenstates that have the same eigenvalue. The question arises whether there are processes in nature that correspond to such ideal quantum measurements and how such processes are dynamically implemented in nature. Here we address this question and present experimental results monitoring the dynamics of a naturally occurring measurement process: the coupling of a trapped ion qutrit to the photon environment. By taking tomographic snapshots during the detection process, we show that the process develops in agreement with the model of an ideal quantum measurement with an average fidelity of 94%.
理想量子测量的存在是量子力学的基本预测之一。理论上，理想测量将量子态投影到测量可观测量的本征基上，同时保持具有相同本征值的本征态之间的相干性。于是问题出现了，自然界中是否存在与这种理想量子测量相对应的过程，以及这些过程在自然界中是如何动态实现的。在这里，我们解决这个问题，并展示监测自然发生的测量过程动力学的实验结果：一个囚禁离子三量子比特与光子环境的耦合。通过在检测过程中拍摄断层扫描快照，我们表明该过程的发展符合理想量子测量模型，平均保真度为94%。
