Single-shot initialization of electron spin in a quantum dot using a short optical pulse

We propose a technique to initialize an electron spin in a semiconductor quantum dot with a single short optical pulse. It relies on the fast depletion of the initial spin state followed by a preferential, Purcell-accelerated deexcitation toward the desired state thanks to a micropillar cavity. We theoretically discuss the limits on initialization rate and fidelity and derive the pulse area for optimal initialization. We show that spin initialization is possible using a single optical pulse down to a few tens of picoseconds wide.