How to dress radio-frequency photons with tunable momentum

TL;DR

This paper presents a method to give radio-frequency photons tunable momentum using magnetic forces and RF pulses, enabling spin-orbit coupling in ultracold atoms without optical transitions or heating.

Contribution

It introduces a novel technique combining magnetic forces and RF pulses to control photon momentum, advancing spin-orbit coupling methods in ultracold atom research.

Findings

Observation of velocity-selective spin-flip transitions

Detection of associated Doppler shifts

Realization of magnetic spin-orbit coupling component

Abstract

We demonstrate how the combination of oscillating magnetic forces and radio-frequency (RF) pulses endows RF photons with tunable momentum. We observe velocity-selective spinflip transitions and the associated Doppler shift. This realizes the key component of purely magnetic spin-orbit coupling schemes for ultracold atoms, which does not involve optical transitions and therefore avoids the problem of heating due to spontaneous emission.