A quantum sensor was developed that could detect communication signals over the entire radio frequency spectrum from 0 to 100 GHz. Such wide spectral coverage by a single antenna is impossible with a traditional receiver system and would require multiple systems of individual antennas, amplifiers, and other components.

Army scientists previously created a quantum receiver that uses highly excited, super-sensitive atoms — known as Rydberg atoms — to detect communications signals. The researchers calculated the receiver’s channel capacity, or rate of data transmission, based on fundamental principles and then achieved that performance experimentally in the lab, improving on other groups’ results by orders of magnitude.

The sensors can be very small and virtually undetectable, giving soldiers a disruptive advantage. Rydberg-atom-based sensors have only recently been considered for general electric field sensing applications including as a communications receiver. While Rydberg atoms are known to be broadly sensitive, a quantitative description of the sensitivity over the entire operational range has never been done.

To assess potential applications, scientists conducted an analysis of the Rydberg sensor’s sensitivity to oscillating electric fields over an enormous range of frequencies, from 0 to 1012 Hertz. The results show that the Rydberg sensor can reliably detect signals over the entire spectrum and compare favorably with other established electric field sensor technologies such as electro-optic crystals and dipole antenna-coupled passive electronics.

In the future, scientists will investigate methods to continue to improve the sensitivity to detect even weaker signals and expand detection protocols for more complicated waveforms.

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