Millisecond spin lifetimes in quantum dots at zero applied magnetic field due to strong electron-nuclear interaction

TL;DR

This paper demonstrates that strong hyperfine interactions in quantum dots enable millisecond electron spin lifetimes at zero magnetic field by polarizing nuclei and forming a stable nuclear spin polaron state.

Contribution

It introduces the concept that electron-nuclear coupling can stabilize electron spins over milliseconds at zero field, a significant step for quantum memory applications.

Findings

Electron spins align with nuclear magnetic fields in quantum dots.

Nuclear polarization feedback stabilizes electron spin polarization.

Millisecond spin lifetimes are achieved at zero magnetic field.

Abstract

A key to achieving ultra-long electron spin memory in quantum dots (QDs) at 0~$T$ is the polarization of the nuclei, such that the electron spin is stabilized along the nuclear magnetic field. We demonstrate that spin-polarized electrons in n-doped QDs align the nuclear field via the hyperfine interaction. A feedback onto the electrons occurs, leading to stabilization of electron polarization. We suggest that the coupled electron-nuclear system forms a rigid nuclear spin polaron state as predicted by I.A.~Merkulov, for which spin memory is retained over millisecond lifetimes.