# Digital Communication with Rydberg Atoms & Amplitude-Modulated Microwave Fields

## TL;DR

This paper demonstrates that room-temperature Rydberg atoms can serve as high-bandwidth, sensitive microwave communication antennas capable of near shot-noise limited data readout and high channel capacity, surpassing classical antenna capabilities.

## Contribution

The study introduces a novel use of Rydberg atoms as microwave communication antennas with high bandwidth and sensitivity, achieving near shot-noise limited readout and high data rates.

## Key findings

- Achieved a channel capacity of up to 8.2 Mbit/s.
- Demonstrated near photon-shot-noise limited readout of 17 GHz microwaves.
- Implemented an 8-state phase-shift-keying digital communication protocol.

## Abstract

Rydberg atoms, with one highly-excited, nearly-ionized electron, have extreme sensitivity to electric fields, including microwave fields ranging from 100 MHz to over 1 THz. Here we show that room-temperature Rydberg atoms can be used as sensitive, high bandwidth, microwave communication antennas. We demonstrate near photon-shot-noise limited readout of data encoded in amplitude-modulated 17 GHz microwaves, using an electromagnetically-induced-transparency (EIT) probing scheme. We measure a photon-shot-noise limited channel capacity of up to 8.2 Mbit/s and implement an 8-state phase-shift-keying digital communication protocol. The bandwidth of the EIT probing scheme is found to be limited by the available coupling laser power and the natural linewidth of the rubidium D2 transition. We discuss how atomic communications receivers offer several opportunities to surpass the capabilities of classical antennas.