Single electron-spin memory with a semiconductor quantum dot

TL;DR

This paper demonstrates a method for storing and reading out the polarization state of light in a single electron spin within a semiconductor quantum dot, enabling quantum information transfer between different physical systems.

Contribution

It introduces a technique for transferring optical polarization to an electron spin in a quantum dot and reading it out via single-photon emission, with extended spin memory.

Findings

Spin memory preserved for over 1000 times the exciton's lifetime

Photon emission shares initial polarization but differs in energy

Quantum information transfer between optical and spin systems

Abstract

We show storage of the circular polarisation of an optical field, transferring it to the spin-state of an individual electron confined in a single semiconductor quantum dot. The state is subsequently readout through the electronically-triggered emission of a single photon. The emitted photon shares the same polarisation as the initial pulse but has a different energy, making the transfer of quantum information between different physical systems possible. With an applied magnetic field of 2 Tesla, spin memory is preserved for at least 1000 times more than the exciton's radiative lifetime.