Magnetic Jones Vector Detection with rf Atomic Magnetometers

We show, theoretically and experimentally, how the absolute orientation and polarization state of radio-frequency (rf) magnetic fields in a transverse two-dimensional (2D) plane can be uniquely determined using two optically pumped atomic magnetometers. In addition, the output signals from these quantum sensors can be readily expressed as a magnetic Jones vector. This composite device can complement electric field detection in finding rf directions or it can be used in applications where the electric field is negligible. The latter is found in a myriad of applications where the source can be modeled as radiating magnetic dipoles in the near-field limit. This tool could be used to characterize the response of a material to rf excitation or to distinguish signal from noise.