Quantum Demodulation of QAM Signals at a Rydberg atomic Homodyne Receiver

Facing the trend of 5G/6G communications toward high spectral efficiency and low power consumption, RF receivers urgently need to overcome the triple challenges of high sensitivity, terahertz (THz) coverage, and system integration. Conventional approaches are limited by electronic thermal noise, band correlation and antenna perturbation effects. In this context, sensors based on the Rydberg atom become a promising alternative, with his large electric dipole moment bringing extremely high sensitivity, inherent frequency selectivity, and the potential to build low-power integrated photonic platforms. This paper describes a Rydberg atomic RF sensor using a quantum coherent mechanism to receive and demodulate quadrature AM signals. The core innovations include: (1) a scheme for 4QAM signal splitting and demodulation within the atomic resonance region via precise signal control; and (2) dynamic, real-time control of the demodulation channels (I/Q paths) by exploiting the phase difference between the local oscillator (LO) and signal (SIG) fields. The proposed architecture can support demodulation of quadrature AM signals, demonstrating its great potential as a versatile next-generation communications platform.