Nuclear Spin Switch in Semiconductor Quantum Dots

TL;DR

This paper demonstrates a nuclear spin switch in semiconductor quantum dots driven by circularly polarized light, revealing bistable nuclear polarization states influenced by external fields and feedback mechanisms.

Contribution

It introduces a novel optical method to control nuclear spin states in quantum dots, showing bistability and threshold behavior dependent on external conditions.

Findings

Nuclei can be driven into bistable states with up to 3 Tesla polarization.

The nuclear spin switch exhibits threshold-like behavior influenced by external magnetic and electric fields.

Feedback from nuclear polarization affects electron-nuclei spin transfer dynamics.

Abstract

We show that by illuminating an InGaAs/GaAs self-assembled quantum dot with circularly polarized light, the nuclei of atoms constituting the dot can be driven into a bistable regime, in which either a threshold-like enhancement or reduction of the local nuclear field by up to 3 Tesla can be generated by varying the intensity of light. The excitation power threshold for such a nuclear spin "switch" is found to depend on both external magnetic and electric fields. The switch is shown to arise from the strong feedback of the nuclear spin polarization on the dynamics of spin transfer from electrons to the nuclei of the dot.