Anomalous broadening in driven dissipative Rydberg systems

TL;DR

This paper reports on the observation of interaction-induced broadening in Rydberg atom transitions within a lattice, revealing how density and excitation influence linewidths and resonant scattering, with implications for quantum information applications.

Contribution

It demonstrates a novel broadening mechanism in driven dissipative Rydberg systems linked to dipole-dipole interactions and provides a unified description of transition widths based on steady-state Rydberg densities.

Findings

Linewidth increases by nearly two orders of magnitude with density and excitation strength.

Resonant excitation rate matches a two-level system with measured linewidth.

Broadening mechanism could negatively impact Rydberg-based quantum proposals.

Abstract

We observe interaction-induced broadening of the two-photon 5s-18s transition in 87Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.