Quantum optics and spin physics with solid-state defect centres

电子或原子核的微小磁矩--自旋--提供了一个物理系统，可以在极长的时间尺度上表现出量子力学行为；在某些情况下，它们可以表现出几秒钟、几分钟甚至几个小时的连贯演化。如果信息被编码成这种自旋的状态，它们的长期相干可以成为未来计算或密码系统的资源，这些系统的计算能力或信息安全从根本上是基于量子力学定律的。同时，自旋的量子态可以成为对其周围环境极其敏感的探测器，为研究其局部环境的性质或高精度测量外部电磁场创造了机会。为了实现基于自旋的量子设备，人们必须找到控制自旋的方法，准备和检测它们的状态，并在不牺牲量子相干特性的情况下设计它们之间的相互作用。

The tiny magnetic moments of electrons or nuclei - spins - offer a physical system that can behave quantum mechanically over extraordinarily long timescales; in some cases they can exhibit coherent evolution for seconds, minutes, or even hours. If information is encoded into the state of such spins, their long-lived coherence can become a resource for future computing or cryptography systems whose computational power or information security is fundamentally based on the laws of quantum mechanics. At the same time, the quantum states of spins can be exquisitely sensitive probes of their surroundings, creating opportunities to study the nature of their local environment or measure external electromagnetic fields with high precision. To realize spin-based quantum devices, one must find ways to control spins, prepare and detect their states, and engineer interactions between them without sacrificing their coherent quantum character.