Amplification without Inversion Enhanced Rydberg‐Atom‐Based Detection of Microwave Electric Fields

ABSTRACT A quantum‐enhanced scheme for microwave (MW) electric (E) field detection is theoretically proposed, utilizing transient amplification without inversion (AWI) in cold 87 Rb atoms. It is achieved by modulating a continuous‐wave coupling laser into a periodic near‐square‐wave pulse, which enables precise control over quantum coherence and induces transient gain. Simulation results demonstrate significant performance enhancements of the AWI scheme compared to conventional electromagnetically induced transparency (EIT) approaches. In comparison, the AWI scheme shows 7.3 times enhanced transient transmission intensity. The reduction of the full width at half maximum from 0.54 × 2π to 0.15 × 2π MHz represents a 72% narrowing of the spectral linewidth, which enables superior spectral resolution and extends the range of measurable Autler‐Townes splitting. Furthermore, the minimum detectable MW E‐field strength of 172.8 nV cm −1 represents an order of magnitude improvement. The robustness of the AWI signal against simulated technical noise is also confirmed. The demonstrated capabilities establish AWI as a promising technique for high‐sensitivity quantum MW electrometry.