Ultrafast optical spin echo for electron spins in semiconductors

TL;DR

This paper demonstrates an all-optical spin echo technique using ultrafast pulses to measure the coherence time T2 of electron spins in semiconductors, enabling faster and cleaner quantum coherence measurements.

Contribution

It introduces a novel ultrafast optical spin echo method for electron spins, surpassing microwave techniques in speed and clarity for T2 measurements.

Findings

Successful measurement of T2 times using optical pulses

Ultrafast optical control reduces dephasing effects

Potential for ultrafast optical dynamic decoupling

Abstract

Spin-based quantum computing and magnetic resonance techniques rely on the ability to measure the coherence time, T2, of a spin system. We report on the experimental implementation of all-optical spin echo to determine the T2 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 T2 measurements of systems with dephasing times T2* fast in comparison to the timescale for microwave control. This demonstration provides a step toward ultrafast optical dynamic decoupling of spin-based qubits.