Simultaneous Detection and Direct Demodulation of Communication Signals Using a Rydberg Atom-Based Sensor

Due to their large dipole moments and polarizability, as well as their long excited-state lifetimes, Rydberg atoms serve as excellent radio-frequency (RF) electric field sensors. In fact, Rydberg atoms can be used as a down-converting RF mixer, whereby an RF-signal is mixed in free-space with a local oscillator (LO), yielding an intermediate frequency (IF). The IF is then detected by measuring the transmission of a weak probe laser which passes through the atomic vapor. This RF-heterodyne technique has been widely demonstrated to be effective in detecting standard communications signals. However, it still requires the use of conventional techniques to demodulate the IF and recover the in-phase (I) and quadrature (Q) components of the signal. Here we demonstrate full atomic demodulation of a communications signal through a dual channel Rydberg sensor which instead utilizes an RF-homodyne technique, whereby the signal is mixed directly to base-band by the atoms (i.e. the IF is set to zero and the signal’s modulation is output directly at DC).