Rydberg atom-based radio frequency sensors: amplitude regime sensing

TL;DR

This paper develops analytic models for Rydberg atom-based RF sensors operating in the amplitude regime, addressing sensitivity limits and thermal motion effects, which enhances understanding and optimization of these sensors.

Contribution

It provides the first analytic expressions for the amplitude regime in Rydberg atom RF sensing, including effects of thermal motion and residual Doppler shifts.

Findings

Analytic expressions for absorption coefficient and sensitivity derived.

Thermal motion and Doppler shifts limit sensor sensitivity.

Models validated over a broad parameter space.

Abstract

Rydberg atom-based radio frequency electromagnetic field sensors are drawing wide-spread interest because of their unique properties, such as small size, dielectric construction, and self-calibration. These photonic sensors use lasers to prepare atoms and read out the atomic response to a radio frequency electromagnetic field based on electromagnetically induced transparency, or related phenomena. Much of the theoretical work has focused on the Autler-Townes splitting induced by the radio frequency wave. The amplitude regime, where the change in transmission observed on resonance is measured to determine electric field strength, has received less attention. In this paper, we deliver analytic expressions that are useful for calculating the absorption coefficient and sensitivity in the amplitude regime. We describe the approximations that we applied to obtain the analytic expressions and demonstrate their validity over a large range of the interesting parameter space. The effect of the thermal motion of the atoms is explicitly addressed. Residual Doppler shifts are shown to limit sensitivity. An analytic expression for the amplitude regime of Rydberg atom-based sensing has not, to our knowledge, been obtained previously. The expressions, approximations and descriptions presented in the paper are important for maximizing the sensitivity of Rydberg atom-based sensors and for providing insight into the physics of multi-level interference phenomena.