Sagnac-enhanced Rydberg superheterodyne receiver with dual-beam interference

Increasing the number of atoms that interact with microwave fields represents a promising strategy for enhancing the sensitivity of Rydberg atom-based superheterodyne receivers. Nevertheless, the practical implementation of this approach is impeded by adverse effects such as excitation saturation of Rydberg atoms and power broadening. Here, we demonstrate enhanced microwave field measurements based on two specific velocity groups of atoms, simultaneously addressed by dual-channel probe beams in a Sagnac loop interferometer. The application of resonance detuning in two-photon excitation enables selective addressing of atoms moving along the beam direction, thereby significantly mitigating atomic transit noise. At 7.97 GHz, our method yields a 3 dB improvement in signal-to-noise ratio (SNR), achieving a sensitivity of 10.7 nV·cm^-1·Hz^-1/2. This approach offers a viable pathway to further improve the sensitivity of Rydberg atom-based microwave electrometers.