Luo Zhouchen, Sun Shuo, Karasahin Aziz, Bracker Allan S, Carter Samuel G, Yakes Michael K, Gammon Daniel, Waks Edo
Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park , Maryland 20742 , United States.
Naval Research Laboratory , Washington , DC 20375 , United States.
Nano Lett. 2019 Oct 9;19(10):7072-7077. doi: 10.1021/acs.nanolett.9b02443. Epub 2019 Sep 9.
Charged quantum dots containing an electron or hole spin are bright solid-state qubits suitable for quantum networks and distributed quantum computing. Incorporating such quantum dot spin into a photonic crystal cavity creates a strong spin-photon interface in which the spin can control a photon by modulating the cavity reflection coefficient. However, previous demonstrations of such spin-photon interfaces have relied on quantum dots that are charged randomly by nearby impurities, leading to instability in the charge state, which causes poor contrast in the cavity reflectivity. Here we demonstrate a strong spin-photon interface using a quantum dot that is charged deterministically with a diode structure. By incorporating this actively charged quantum dot in a photonic crystal cavity, we achieve strong coupling between the cavity mode and the negatively charged state of the dot. Furthermore, by initializing the spin through optical pumping, we show strong spin-dependent modulation of the cavity reflectivity, corresponding to a cooperativity of 12. This spin-dependent reflectivity is important for mediating entanglement between spins using photons, as well as generating strong photon-photon interactions for applications in quantum networking and distributed quantum computing.
包含电子或空穴自旋的带电量子点是适用于量子网络和分布式量子计算的明亮固态量子比特。将这种量子点自旋整合到光子晶体腔中会创建一个强大的自旋 - 光子界面，其中自旋可以通过调制腔反射系数来控制光子。然而，此前此类自旋 - 光子界面的演示依赖于被附近杂质随机充电的量子点，这导致电荷状态不稳定，进而造成腔反射率的对比度不佳。在此，我们展示了一种使用通过二极管结构确定性充电的量子点的强大自旋 - 光子界面。通过将这个主动充电的量子点纳入光子晶体腔，我们实现了腔模与量子点负电荷态之间的强耦合。此外，通过光泵浦初始化自旋，我们展示了腔反射率的强烈自旋依赖调制，对应于12的协同性。这种自旋依赖反射率对于利用光子介导自旋之间的纠缠以及产生用于量子网络和分布式量子计算应用的强光子 - 光子相互作用非常重要。
