Rydberg-atom electrical-field sensors – a case study of dual use of quantum sensors

Rydberg atoms in a room-temperature gas cell can be used for very sensitive detection of electrical fields in the megahertz to terahertz region. Sensors can be small, non-absorbing and are not destroyed by very strong fields with full-optical readout. Applications in communications, imaging and radar, and in metrology are foreseen. Military research is active, particularly in the USA, funding at first academic institutions, but increasingly development is contracted to commercial firms. There are similarities and differences between civilian and military applications, with interaction between both fields. Rydberg-atom electrical-field sensors are a general-purpose technology, and do not directly provide new offensive or threatening military options. No strong negative impacts on international security and peace are foreseen. Academic researchers have taken military funding readily.