Atomic Magnetometer Multisensor Array for rf Interference Mitigation and Unshielded Detection of Nuclear Quadrupole Resonance

Whether in medical or security applications, magnetic resonance spectroscopy is very useful for detecting faint signals from target compounds. However, interference (from $e.g.$ a local radio station) can be a problem. The authors devise optical atomic-gas detectors that work in unshielded environments, and without cryogenic cooling---important advantages for real-world use. These sensitive, compact systems offer baseline noise at the quantum limit.