Coherent two-colour manipulation of a single QD-confined spin

InGaAs量子点（QD）在受限自旋和明确定义的光学模式之间提供了非常强的界面。在这里，我们开发了一种全光学技术进行相干控制这个单一的自旋，使用受激拉曼过程。该技术结合了两个塞曼分裂自旋态之间的直接微波驱动的灵活性，具有光学方案的速度。我们证明了完全控制的旋转轴上的布洛赫球的自旋，旁边的单旋转保真度为97%，等于预期使用传统的自旋控制技术。将这种频率选择性的共振控制技术与狭窄的核自旋浴相结合，使我们能够在该系统的裸相干时间之外进行相干操作，这意味着我们可以通过耦合到受限的中心自旋来控制单个核自旋。

InGaAs quantum dots (QDs) give a very strong interface between a confined spin and well-defined optical modes. Here, we develop an all-optical technique for performing coherent control of this single spin, using a stimulated Raman process. This technique incorporates the flexibility of a direct microwave drive between the two Zeeman-split spin states with the speed of an optical scheme. We demonstrate full control over the rotation axis of the spin on the Bloch sphere, alongside a single-rotation fidelity of 97%, equalling that expected using conventional spin control techniques. Combining this frequency-selective, resonant control technique with a narrowed nuclear spin bath allows us to perform coherent operations well beyond the bare coherence times for this system, and means that we can look ahead to performing control of individual nuclear spins through their coupling to the confined central spin.