Coupling light to a nuclear spin gas with a two-photon linewidth of five millihertz

TL;DR

This paper demonstrates a coherent, bidirectional optical interface with noble-gas nuclear spins mediated by alkali atoms, achieving record coherence times and enabling optical manipulation of long-lived nuclear spins.

Contribution

It introduces a novel method to couple light with noble-gas spins via alkali atoms, achieving unprecedented coherence times and high-contrast two-photon spectra.

Findings

Record two-photon linewidth of 5 mHz at room temperature

Achieved one-minute coherence time for noble-gas spins

Demonstrated coherent bidirectional coupling between light and noble-gas spins

Abstract

Nuclear spins of noble gases feature extremely long coherence times but are inaccessible to optical photons. Here we realize a coherent interface between light and noble-gas spins that is mediated by alkali atoms. We demonstrate the optical excitation of the noble-gas spins and observe the coherent back-action on the light in the form of high-contrast two-photon spectra. We report on a record two-photon linewidth of 5$\pm$0.7 mHz (millihertz) above room-temperature, corresponding to a one-minute coherence time. This experiment provides a demonstration of coherent bi-directional coupling between light and noble-gas spins, rendering their long-lived spin coherence accessible for manipulations in the optical domain.