Coherent coupling of alkali atoms by random collisions

TL;DR

This paper demonstrates that random spin-exchange collisions in warm alkali vapors can coherently couple different alkali species, allowing one to inherit magnetic properties from the other, with controllable coupling via magnetic field strength.

Contribution

The study reveals a novel coherent coupling mechanism between alkali species mediated by collisions, supported by experimental, theoretical, and analytical mode-mixing analysis.

Findings

Potassium inherits rubidium's magnetic properties including T1, T2, and gyromagnetic ratio.

The coupling strength can be controlled by adjusting the magnetic field.

The phenomena are explained through modes-mixing of the two species via spin-exchange collisions.

Abstract

Random spin-exchange collisions in warm alkali vapor cause rapid decoherence and act to equilibriate the spin state of the atoms. In contrast, here we demonstrate experimentally and theoretically a coherent coupling of one alkali specie to another specie, mediated by these random collisions. We show that, the minor specie (potassium) inherits the magnetic properties of the dominant specie (rubidium), including its lifetime (T1), coherence time (T2), gyromagnetic ratio, and SERF magnetic-field threshold. We further show that this coupling can be completely controlled by varying the strength of the magnetic field. Finally, we explain these phenomena analytically by modes-mixing of the two species via spin-exchange collisions.