Rydberg atom electrometer for k-vector measurements and reception of polarization encoded symbols.

We present a three-dimensional simultaneous rf polarimeter and k-vector sensor based on a Rydberg atom electrometer. The sensor measures the full polarization ellipse and thus determines the k-vector through an extension of current rf heterodyne techniques to three dimensions. We present the performance of this new sensor, including the ability to receive symbols encoded in the polarization of the input field, and the dependence of k-vector measurements on the input field ellipticity. We find that improvements to the sensor can be made through modeling and accounting for systematic effects due to reflections of rf fields in the sensing region. Additionally, we investigate a trade-off between system size and the range of measurable k-vectors, as the measured signal is averaged away for large sensing regions and k-vectors at large angles.