Enhanced microwave electrometry in weakly interacting Rydberg atoms using a modified formula

This study addresses the restrictions imposed by nonlocal van der Waals (vdW) and dipole-dipole (DD) interactions on the microwave electrometry in cold Rydberg atoms driven into the four-level cascade configuration with relatively high excitation densities. Utilizing the mean-field superatom model, we examine, in particular, the effects of vdW and DD interactions on microwave-controlled transmission spectra of a probe field in the regime of electromagnetically induced transparency (EIT). In response to spectral shifts depending on such Rydberg interactions, we propose a modified formula for correctly describing the nonlinear relationship between the microwave electric field and the splitting of two EIT peaks, which could enhance the measurement accuracy. This formula also extends the lower limit set by a certain measurement accuracy into the nonlinear response region by approximately five times, effectively mitigating the restrictions imposed by vdW and DD interactions. Our findings suggest that an accurate measurement of weak microwave electric fields could be achieved under both high and low-density conditions through data correction, yet without altering the experimental method. This research provides an alternative solution for microwave electrometry in weakly interacting atomic gases and highlights its potential applications in integrated quantum devices.