Optical detection of single-electron spin decoherence in a quantum dot

We propose a method based on optically detected magnetic resonance (ODMR) to measure the decoherence time $T_2$ of a single electron spin in a semiconductor quantum dot. The electron spin resonance (ESR) of a single excess electron on a quantum dot is probed by circularly polarized laser excitation. Due to Pauli blocking, optical excitation is only possible for one of the electron-spin states. The photoluminescence is modulated due to the ESR which enables the measurement of electron-spin decoherence. We study different possible schemes for such an ODMR setup.