# Spin temperature concept verified by optical magnetometry of nuclear spins

## TL;DR

This paper demonstrates a non-perturbative optical method to control and verify the spin temperature concept in nuclear spins within GaAs microcavities, confirming theoretical predictions despite quadrupole interactions.

## Contribution

It introduces a novel optical control technique for nuclear spin systems and experimentally verifies the spin temperature theory in the presence of quadrupole interactions.

## Key findings

- Nuclear spins follow the spin-temperature theory predictions.
- Quadrupole interactions do not disrupt nuclear spin thermalisation.
- Potential for deep cooling and spin-ordered states in semiconductors.

## Abstract

We develop a method of non-perturbative optical control over adiabatic remagnetisation of the nuclear spin system and apply it to verify the spin temperature concept in GaAs microcavities. The nuclear spin system is shown to exactly follow the predictions of the spin-temperature theory, despite the quadrupole interaction that was earlier reported to disrupt nuclear spin thermalisation. These findings open a way to deep cooling of nuclear spins in semiconductor structures, with a prospect of realisation of nuclear spin-ordered statesfor high fidelity spin-photon interfaces.