Digital communication with Rydberg atoms and amplitude-modulated microwave fields

Rydberg atoms, with one highly excited, nearly ionized electron, have extreme sensitivity to electric fields, including microwave fields ranging from 100MHz to over 1 THz. Here, we show that roomtemperature 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(-1) 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 communication receivers offer several opportunities to surpass the capabilities of classical antennas. Published by AIP Publishing.