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

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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.