Atom-based quantum receiver for amplitude- and frequency-modulated baseband signals in high-frequency radio communication

TL;DR

This paper demonstrates an atom-based quantum receiver using cesium Rydberg atoms and electromagnetically induced transparency to retrieve amplitude- and frequency-modulated signals from high-frequency microwave carriers in real-time, without electronic demodulation.

Contribution

The work introduces a novel optical quantum receiver capable of directly retrieving baseband signals from microwave carriers using Rydberg atom spectroscopy, applicable across a wide frequency range.

Findings

Successfully retrieved baseband signals modulated onto 16.98 GHz carrier.

Demonstrated real-time optical detection without electronic demodulation.

Applicable to carrier frequencies from ~1 GHz to hundreds of GHz.

Abstract

An optical probe of cesium Rydberg atoms generated in a thermal vapor cell is used to retrieve a baseband signal modulated onto a 16.98-GHz carrier wave in real-time, demonstrating an atom-based quantum receiver suitable for microwave communication. The 60$S_{1/2}$ Rydberg level of cesium atoms in the cell is tracked via electromagnetically induced transparency (EIT), an established laser-spectroscopic method. The microwave carrier is resonant with the 60$S_{1/2}$ $\rightarrow$ 60$P_{1/2}$ Rydberg transition, resulting in an Autler-Townes (AT) splitting of the EIT signal. Amplitude modulation of the carrier wave results in a corresponding modulation in the optically retrieved AT splitting. Frequency modulation causes a change in relative height of the two AT peaks, which can be optically detected and processed to retrieve the modulation signal. The optical retrieval of the baseband signal does not require electronic demodulation. The method is suitable for carrier frequencies within a range from $\sim 1$~GHz to hundreds of GHz. The baseband bandwidth, which is $\sim$~20~Hz in the present demonstration, can be increased by faster spectroscopic sampling.