Fast Spin State Initialization in a Singly Charged InAs-GaAs Quantum Dot by Optical Cooling

Abstract

Quantum computation requires a continuous supply of rapidly initialized qubits for quantum error correction. Here, we demonstrate fast spin state initialization with near unity efficiency in a singly charged quantum dot by optically cooling an electron spin. The electron spin is successfully cooled from 5 to 0.06 K at a magnetic field of 0.88 T applied in Voigt geometry. The spin cooling rate is of order ${10}^9{\mathrm{s}}^{-1}$, which is set by the spontaneous decay rate of the excited state.