Simultaneous Detection, Demodulation, and Angle-of-Arrival Determination of Communication Signals Using a Dual Ladder Rydberg Receiver
In a typical Rydberg mixer, modulated communication signals are detected using a radio frequency (RF) heterodyne technique. The mixer outputs an intermediate frequency (IF), which must be filtered and mixed down to baseband. In this work, we apply an RF-homodyne technique to demonstrate simultaneous detection and a direct, baseband readout of the in-phase (I) and quadrature (Q) components of standard communication signals using a dual ladder Rydberg receiver. We further show that the inherent polarization sensitivity of this receiver can be used to determine the signal's angle of arrival. We also compare the dual ladder system with a typical Rydberg mixer. The RF-heterodyne-based system's maximum detectable symbol rate is constrained by a signal amplitude which decays with the heterodyne field's detuning from the Rydberg-Rydberg atomic transition used to detect the signal, but the dual ladder design is not subject to this limitation. However, the dual ladder system is more sensitive to low-frequency noise. As a result, its performance is degraded relative to its conventional counterpart when subjected to pink noise. We show that once pink noise effects have been accounted for, both systems behave comparably.