A millimeter-wave atomic receiver

Rydberg quantum sensors are sensitive to radio-frequency fields across an ultra-wide frequency range spanning megahertz to terahertz electromagnetic waves resonant with Rydberg atom dipole transitions. Here we demonstrate an atomic millimeter-wave heterodyne receiver employing continuous-wave lasers stabilized to an optical frequency comb. We characterize the atomic receiver in the W-band at signal frequency of $f$=95.992512~GHz, and demonstrate a sensitivity of 7.9$\mu$V/m/$\sqrt{Hz}$ and a linear dynamic range of 70dB. We develop frequency selectivity metrics for atomic receivers and demonstrate their use in our millimeter-wave receiver, including signal rejection levels at signal frequency offsets $\Delta f/f$ = 10$^{-4}$, 10$^{-5}$ and 10$^{-6}$, 3-dB, 6-dB, 9-dB and 12-dB bandwidths, filter roll-off, and shape factor analysis. Our work represents an important advance towards future studies and applications of atomic receiver science and technology and in weak millimeter-wave and high-frequency signal detection.