山西大学激光光谱研究所

This study systematically investigates the interaction mechanisms between microwave fields and multi-level transitions through trap-loss spectroscopy of ultracold cesium Rydberg atoms. By combining circularly polarized light with microwave field manipulation, we reveal a composite broadening effect dominated by laser power broadening (accounting for 83% of the total), while also observing a square-root power dependence of broadening in weak fields and linear-power-dependent doublet splitting in strong fields. These findings not only deepen our understanding of Rydberg atom-microwave coupling dynamics, but also establish a novel real-time microwave electric field detection technique based on spectral analysis, providing new tools for precision measurement and quantum control.

Our research group has proposed and experimentally validated a Rydberg-atom-based isotropic antenna that overcomes the fundamental limitation of classical antennas constrained by the hairy ball theorem, which prevents ideal isotropic responses. Theoretical analysis confirms that its measurements are direction-independent with respect to incident radio-frequency fields while offering inherent SI traceability and ultrawideband capabilities. Experimentally demonstrated in microwave and terahertz regimes, this approach achieves isotropic deviations below 5 dB over full solid angle and as low as 0.28 dB in single-plane measurements—representing at least 15 dB improvement over classical antennas. This atomic-based methodology shows significant application potential in radio-frequency electrometry and full space coverage communications.