title: Ultrafast optical spin echo for electron spins in semiconductors.
abstract: Spin-based quantum computing and magnetic resonance techniques rely on the ability to measure the coherence time T(2) of a spin system. We report on the experimental implementation of all-optical spin echo to determine the T(2) time of a semiconductor electron-spin system. We use three ultrafast optical pulses to rotate spins an arbitrary angle and measure an echo signal as the time between pulses is lengthened. Unlike previous spin-echo techniques using microwaves, ultrafast optical pulses allow clean T(2) measurements of systems with dephasing times (T_{2};{*}) fast in comparison to the time scale for microwave control. This demonstration provides a step toward ultrafast optical dynamic decoupling of spin-based qubits.
authors: Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305-4088, USA. sclark4@stanford.edu
authors: Susan M
authors: SM
authors: Clark
authors: Kai-Mei C
authors: KM
authors: Fu
authors: Qiang
authors: Q
authors: Zhang
authors: Thaddeus D
authors: TD
authors: Ladd
authors: Colin
authors: C
authors: Stanley
authors: Yoshihisa
authors: Y
authors: Yamamoto