Quantum information processing (QIP) with solid state spin qubits strongly depends on the efficient initialisation of the qubit’s desired charge state. While the negatively charged tin-vacancy (SnV⁻) centre in diamond has emerged as an excellent platform for realising QIP protocols due to long spin coherence times at liquid helium temperature and lifetime limited optical transitions, its usefulness is severely limited by termination of the fluorescence under resonant excitation. Here, we unveil the underlying charge cycle, potentially applicable to all group IV-vacancy (G4V) centres, and exploit it to demonstrate highly efficient and rapid initialisation of the desired negative charge state of single SnV centres while preserving long term stable optical resonances. In addition to investigating the optical coherence, we all-optically probe the coherence of the ground state spins by means of coherent population trapping and find a spin dephasing time of 5(1) μs. Furthermore, we demonstrate proof-of-principle single shot spin state readout without the necessity of a magnetic field aligned to the symmetry axis of the defect.

具有固态自旋量子位的量子信息处理 (QIP) 很大程度上取决于量子位所需电荷状态的有效初始化。而带负电的锡空位（SnV ^-) 由于在液氦温度下自旋相干时间长且光跃迁寿命有限，金刚石中心已成为实现 QIP 协议的绝佳平台，其实用性受到共振激发下荧光终止的严重限制。在这里，我们揭示了潜在的电荷循环，可能适用于所有 IV 族空位（G4V）中心，并利用它来证明单个 SnV 中心所需负电荷状态的高效和快速初始化，同时保持长期稳定的光学共振。除了研究光学相干性外，我们还通过相干种群捕获全光学地探测基态自旋的相干性，并发现自旋相移时间为 5(1)  μs。此外，我们展示了原理证明的单次自旋状态读数，而无需与缺陷的对称轴对齐的磁场。