Closed-loop interferometry and multiplexing in Rydberg atoms for improved electric field sensing

Electric field sensors based on Rydberg atoms in atomic vapor cells allow for optical readout of the phase of the incident RF fields in an all-dielectric environment. Due to the quantum mechanical nature of the sensing mechanism, this allows for novel functionality that we explore here. First, we describe the use of a closed-loop scheme of driven transitions that enables phase-sensitive RF detection using a phase reference at a very different frequency from the RF signal. This is the first step toward all-optical phase-sensitive RF detection carrying IQ data. We also describe the use of two independent quantum mechanical Rydberg excitation ladders that enables multiplexing on the same Rydberg state for simultaneous and independent measurements. We demonstrate this capability through polarization-resolved measurements within the same sensing volume. These results point the way towards increased functionality and a broader application space for Rydberg atom-based electric field sensing.