Nonlocal nonlinear response of thermal Rydberg atoms and modulational instability in absorptive nonlinear media

TL;DR

This paper investigates the nonlocal nonlinear response of thermal Rydberg atoms under electromagnetically induced transparency and introduces a model for modulational instability in absorptive nonlinear media, revealing early-stage MI effects.

Contribution

It provides an analytical form for the nonlocal nonlinear response of thermal Rydberg atoms and proposes a generalized model for modulational instability in absorptive media.

Findings

Analytical expression for nonlocal nonlinear atomic response.

Prediction of modulational instability effects at short propagation distances.

Distinct behavior of MI in absorptive versus purely dispersive media.

Abstract

Nonlinear and nonlocal effects are discussed in the interaction of laser fields with thermal Rydberg atoms in electromagnetically induced transparency configuration. We show that under the crucial approximation that the time variation in the dipole-dipole interactions due to atomic motions can be neglected in an ensemble average, an analytical form can be obtained for the nonlocal nonlinear atomic response of the thermal medium, and study it for different parameter cases. We further propose a generalized model to describe the modulational instability (MI) in absorptive nonlinear media, in order to understand the propagation dynamics in the thermal Rydberg medium. Interestingly, this model predicts that at short propagation distances, each wave component exhibits the MI effect in absorptive nonlinear media, unlike in the purely dispersive case.