Spatially-resolved control of fictitious magnetic fields in a cold atomic ensemble

TL;DR

This paper demonstrates a method for spatially-resolved control of atomic spins using a shaped laser beam to induce Zeeman-like ac-Stark shifts, enabling complex manipulations like collapse-and-revival behaviors in cold rubidium atoms.

Contribution

It introduces a technique for precise spatial control of atom-photon interactions via beam shaping to mitigate inhomogeneity-induced decoherence in cold atomic ensembles.

Findings

Achieved spin rotations of 15 radians within a single precession lifetime.

Mitigated inhomogeneity-induced dephasing through beam shaping.

Demonstrated collapse-and-revival phenomena by imprinting patterns on the atomic ensemble.

Abstract

Effective and unrestricted engineering of atom-photon interactions requires precise spatially-resolved control of light beams. The significant potential of such manipulations lies in a set of disciplines ranging from solid state to atomic physics. Here we use a Zeeman-like ac-Stark shift of a shaped laser beam to perform rotations of spins with spatial resolution in a large ensemble of cold rubidium atoms. We show that inhomogeneities of light intensity are the main source of dephasing and thus decoherence, yet with proper beam shaping this deleterious effect is strongly mitigated allowing rotations of 15 rad within one spin-precession lifetime. Finally, as a particular example of a complex manipulation enabled by our scheme, we demonstrate a range of collapse-and-revival behaviours of a free-induction decay signal by imprinting comb-like patterns on the atomic ensemble.