Ultrafast optical spin echo for electron spins in semiconductors

摘要

Spin-based quantum computing and magnetic resonance techniques rely on theability to measure the coherence time, T2, of a spin system. We report on theexperimental implementation of all-optical spin echo to determine the T2 timeof a semiconductor electron-spin system. We use three ultrafast optical pulsesto rotate spins an arbitrary angle and measure an echo signal as the timebetween pulses is lengthened. Unlike previous spin-echo techniques usingmicrowaves, ultrafast optical pulses allow clean T2 measurements of systemswith dephasing times T2* fast in comparison to the timescale for microwavecontrol. This demonstration provides a step toward ultrafast optical dynamicdecoupling of spin-based qubits.