Optical protection of alkali-metal atoms from spin relaxation

TL;DR

This paper introduces an optical method that uses a single off-resonant laser to significantly reduce spin relaxation in alkali-metal atoms, enhancing coherence times and stability in vapor-based systems.

Contribution

The authors develop and experimentally validate a novel optical technique that synchronizes hyperfine precession to suppress relaxation in alkali-metal spins, improving coherence and stability.

Findings

Achieved up to ninefold reduction in decoherence in cesium vapor

Protected spins from spin-exchange relaxation and wall depolarization

Enhanced spin precession quality factor and stable gyromagnetic ratio

Abstract

We present an optical technique for suppressing relaxation in alkali-metal spins using a single off-resonant laser beam. The method harnesses a physical mechanism that synchronizes Larmor precession in the two hyperfine manifolds, protecting magnetic coherence from relaxation caused by spin-exchange and other hyperfine-changing collisions. We experimentally demonstrate up to a ninefold reduction in decoherence of warm cesium vapor, achieving simultaneous protection from both spin-exchange relaxation and partial depolarization from coated cell walls. The technique substantially enhances the spin precession quality factor and maintains a stable gyromagnetic ratio independent of spin polarization, even under frequent collisions. These findings offer a pathway for mitigating dominant relaxation channels in alkali-metal-based applications and experiments, particularly in anti-relaxation-coated cells.