Three-photon Rydberg atom electrometry with enhanced sensitivity

In this work, we present a high-sensitivity, all-optical, atom-based radio-frequency electrometry technique, implemented via a collinear three-photon excitation scheme in a room-temperature cesium vapor cell. By employing a wave-vector matching condition unique to cesium, our approach reduces the residual Doppler broadening so that it does not dominate the electromagnetically induced absorption linewidth, achieving linewidths below 200 kHz. The narrow linewidth enables the expansion of the self-calibrated Autler-Townes sensing regime and increased sensitivity when compared to methods where Doppler broadening dominates the linewidth. In this paper, we report our latest sensitivity measurements which successfully detected radio-frequency (RF) Rabi frequencies of 2π×43 kHz using a 480 kHz measurement bandwidth at 10.7 GHz, corresponding to a sensitivity of 45 nV/cm/ √ Hz. The results of our experiment show a thirteen-fold improvement compared to our previously reported findings for all-optical atom-based electrometry. Our measurements demonstrate the ability to detect time-varying signals suitable for radar and communication applications with high sensitivity.