Phase-resolved atomic imaging of millimeter-wave fields

All-optical, phase-sensitive measurements of radio-frequency (RF) electric fields in Rydberg atom vapors are realized by introducing coherent phase references via optical modulation, forming interferometric loops within the internal Hilbert space of atoms [1]. In this talk, we present recent work extending this method to millimeter-wave detection using constructed interferometric loops in the cesium state space ${6P_{3/2}, 41S_{1/2}, 42S_{1/2}, 41P_{3/2}}$, and apply it to position-resolved amplitude and phase imaging of over-the-air 60 GHz fields.  A key enabling technology for access to millimeter-wave transitions is a phase-stable optical phase-locked loop (OPLL) operating at laser frequency offsets of 60 GHz and above. We report on the development and fidelity characterization of a 60 GHz OPLL and demonstrate full-field amplitude and phase imaging of a millimeter-wave antenna near field at optical diffraction-limited spatial resolution using a wide-area atomic vapor-cell imager.