  Developing microwave electric field sensing based on Rydberg atom has
received significant attention due to its unique advantages. However, achieving
effective coupling between Rydberg atom and the microwave electric field in the
sensing process is a challenging problem that greatly impacts the sensitivity.
To address this, we propose the use of a microwave resonant cavity to enhance
the effective coupling between the Rydberg atoms and the microwave electric
field. In our experiment, we use a three-photon excitation scheme to prepare
Rydberg atoms, make measurements of electric fields without and with a
microwave cavity in which the vapor cell is put inside. Through experimental
testing, we achieve an 18 dB enhancement of power sensitivity. The experiment
shows an effective enhancement in electric field pulse signal detection. This
result provides a promising direction for enhancing the sensitivity of Rydberg
atomic electric field sensors and paves the way for their application in
precision electric field measurements.
