Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
School of Electrical and Computer Engineering, Department of Physics and Astronomy, The University of Oklahoma, 110 West Boyd Street, Norman, OK, 73019, USA.
Nat Commun. 2023 Jul 5;14(1):3977. doi: 10.1038/s41467-023-39568-1.
Rapid, high-fidelity single-shot readout of quantum states is a ubiquitous requirement in quantum information technologies. For emitters with a spin-preserving optical transition, spin readout can be achieved by driving the transition with a laser and detecting the emitted photons. The speed and fidelity of this approach is typically limited by low photon collection rates and measurement back-action. Here we use an open microcavity to enhance the optical readout signal from a semiconductor quantum dot spin state, largely overcoming these limitations. We achieve single-shot readout of an electron spin in only 3 nanoseconds with a fidelity of (95.2 ± 0.7)%, and observe quantum jumps using repeated single-shot measurements. Owing to the speed of our readout, errors resulting from measurement-induced back-action have minimal impact. Our work reduces the spin readout-time well below both the achievable spin relaxation and dephasing times in semiconductor quantum dots, opening up new possibilities for their use in quantum technologies.
快速、高保真的单量子态读取是量子信息技术中普遍存在的要求。对于具有自旋守恒光学跃迁的发射器，可以通过用激光驱动跃迁并检测发射的光子来实现自旋读取。这种方法的速度和保真度通常受到低光子收集率和测量反作用的限制。在这里，我们使用开放式微腔来增强半导体量子点自旋态的光学读出信号，在很大程度上克服了这些限制。我们仅用 3 纳秒就实现了电子自旋的单量子态读取，保真度为（95.2±0.7）%，并通过重复的单量子态测量观察到量子跃迁。由于我们的读取速度很快，测量反作用引起的误差影响很小。我们的工作将自旋读取时间大大缩短至半导体量子点中可实现的自旋弛豫和退相时间以下，为它们在量子技术中的应用开辟了新的可能性。
