Harmonic and Intermodulation Distortion in Atomic Quantum Receivers*

We report here on the measurement and characterization of non-linear behavior and spurious response of a Rydberg atomic heterodyne receiver. Single-tone and two-tone testing procedures are developed and implemented for measurement of harmonic and inter-modulation distortion in Rydberg atomic receivers based on multi-photon Rydberg spectroscopy and radio-frequency heterodyne signal detection in an atomic vapor. For a predetermined set of atomic receiver parameters and RF carrier waves in the SHF band near-resonant to a cesium Rydberg transition, we measure and characterize atomic receiver selectivity, bandwidth, roll-off, compression point (P1dB), second order (IP2) and third order (IP3) intercepts, and spur-free dynamic range. Receiver intermodulation distortion is characterized for the case of an interfering signal wave applied at two frequency offsets relative to the near-resonant reference local oscillator, ∆F/F = 10⁻⁴ at 6 dB and 10⁻⁶ at 22 dB single-tone bandwidths, respectively. We observe that under suitable operating conditions the atomic receiver can exhibit a suppression of harmonic and inter-modulation distortion relative to that of classical receiver mixer amplifiers.  Ref. https://arxiv.org/abs/2412.16366