Seems like a way to directly sense the prescence of electromagnetic fields without first confining them to a wire with an antenna.

Practically speaking, I guess antennas are shaped to work best in a specific range, so now you don’t need multiple antennas? Also there are some cases where just the presence of an antenna would be counterproductive, or simply infeasible, for instance measuring electric fields in a waveguide. Here are some examples from another article:

> Furthermore, the use of small vapor cells allows spatially-localized observations of electric field strengths such as, for example, at points within a microwave wave guide without perturbing the local field as would introduction of an antenna. Rydberg atom measurements can also be directly related to known physical constants and can therefore provide accurate absolute electric field values that can be used to calibrate more conventional antenna-receiver combinations.

https://www.openaccessgovernment.org/rydberg-atoms-quantum-e...