Direct observation of the optical Magnus effect with a trapped ion

TL;DR

This paper demonstrates the direct observation of an optical Magnus effect analog using a trapped calcium ion, revealing spin-dependent transverse displacements caused by intrinsic light polarization effects.

Contribution

It provides the first direct spatial mapping of the optical Magnus effect in a trapped ion system, highlighting polarization-gradient interactions relevant to quantum control.

Findings

Observed spin-dependent transverse displacement of several 100 nm.

Characterized polarization gradients induced by tight beam focusing.

Established the physical basis for polarization-gradient interactions in quantum control.

Abstract

We directly observe and spatially map an optical analog of the Magnus effect, where intrinsic spin-orbit-like coupling of light generates a spin-dependent transverse displacement of the atom-light interaction profile for a $^{40}$Ca$^+$ ion. Probed on a quadrupole transition using a tightly focused beam, we observe displacements of the maximum in the profile of the effective interaction by several 100 nm originating from intrinsic longitudinal electric field components beyond the paraxial approximation. The tight focus of the beam induces additional transverse polarization gradients, which we characterize through a phase-sensitive measurement and spatial maps for different beam configurations. The results establish the physical basis of polarization-gradient interactions relevant to optical tweezer-based quantum control.