Determining the Angle-of-Arrival of an Radio-Frequency Source with a Rydberg Atom-Based Sensor

TL;DR

This paper demonstrates a novel Rydberg atom-based sensor that uses phase measurements within atomic vapor to determine the angle-of-arrival of RF signals with high precision, validated through experiments and simulations.

Contribution

It introduces a new method employing Rydberg atoms and electromagnetically induced transparency for RF direction finding, achieving sub-wavelength phase measurement accuracy.

Findings

Successfully measured phase differences at 19.18 GHz for various angles

Results agree with full-wave simulations and theoretical models

Demonstrates potential for high-precision RF source localization

Abstract

In this work, we demonstrate the use of a Rydberg atom-based sensor for determining the angle-of-arrival of an incident radio-frequency (RF) wave or signal. The technique uses electromagnetically induced transparency in Rydberg atomic vapor in conjunction with a heterodyne Rydberg atom-based mixer. The Rydberg atom mixer measures the phase of the incident RF wave at two different locations inside an atomic vapor cell. The phase difference at these two locations is related to the direction of arrival of the incident RF wave. To demonstrate this approach, we measure phase differences of an incident 19.18 GHz wave at two locations inside a vapor cell filled with cesium atoms for various incident angles. Comparisons of these measurements to both full-wave simulation and to a plane-wave theoretical model show that these atom-based sub-wavelength phase measurements can be used to determine the angle-of-arrival of an RF field.