Fujita Takafumi, Morimoto Kazuhiro, Kiyama Haruki, Allison Giles, Larsson Marcus, Ludwig Arne, Valentin Sascha R, Wieck Andreas D, Oiwa Akira, Tarucha Seigo
Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan.
Nat Commun. 2019 Jul 16;10(1):2991. doi: 10.1038/s41467-019-10939-x.
Gate-defined quantum dots (QDs) are such a highly-tunable quantum system in which single spins can be electrically coupled, manipulated, and measured. However, the spins in gate-defined QDs are lacking its interface to free-space photons. Here, we verify that a circularly-polarized single photon can excite a single electron spin via the transfer of angular momentum, measured using Pauli spin blockade (PSB) in a double QD. We monitor the inter-dot charge tunneling which only occur when the photo-electron spin in one QD is anti-parallel to the electron spin in the other. This allows us to detect single photo-electrons in the spin-up/down basis using PSB. The photon polarization dependence of the excited spin state was finally confirmed for the heavy-hole exciton excitation. The angular momentum transfer observed here is a fundamental step providing a route to instant injection of spins, distributing single spin information, and possibly towards extending quantum communication.
栅极定义的量子点（QDs）是一种高度可调谐的量子系统，其中单个自旋可以进行电耦合、操纵和测量。然而，栅极定义的量子点中的自旋缺乏与自由空间光子的接口。在这里，我们验证了圆偏振单光子可以通过角动量转移激发单个电子自旋，这是在双量子点中使用泡利自旋阻塞（PSB）测量的。我们监测仅在一个量子点中的光电子自旋与另一个量子点中的电子自旋反平行时才会发生的点间电荷隧穿。这使我们能够使用PSB在自旋向上/向下基中检测单个光电子。最终证实了重空穴激子激发下激发自旋态的光子偏振依赖性。这里观察到的角动量转移是一个基本步骤，为自旋的即时注入、单自旋信息的分布以及可能朝着扩展量子通信提供了一条途径。
