A Rydberg atom is a special type of atom characterized by a high principal quantum number. Electric field sensors based on Rydberg atoms have received widespread attention due to their high polarizability. However, there is currently little research on the use of Rydberg atoms for direct current (DC) or low-frequency electric fields, mainly due to the shielding effect of atomic vapor cells in low-frequency electric fields, which makes accurate measurement of the electric fields extremely challenging.

In this paper, we construct a Rydberg ladder configuration by using probe laser at 852 nm and coupling laser at 510 nm in a room-temperature cesium vapor cell with integrated electrode plates, thereby enabling the realizing of a Floquet-EIT (electromagnetically induced transparency) spectrum dressed by a radio frequency (RF) field in the presence of a DC electric field. We further study the influence of DC electric field on spectral characteristic. Experimentally, it is observed that when only the RF electric field is applied, the EIT spectrum displays solely even-order sidebands. Furthermore, when both the RF field and the DC electric field are simultaneously present, the first-order sideband signal of the Floquet-EIT is observed. As the intensity of the DC electric field increases, the amplitude of the first-order sideband gradually increases. However, increasing the DC electric field to a sufficient magnitude induces sideband interference, which leads the sideband amplitudes to decrease. Furthermore, increasing the RF frequency can alleviate the interference effects induced by the DC electric field on the first-order sideband. Finally, comparing the relative standard deviation of the sideband amplitudes of the Floquet-EIT spectra with the frequency shifts of the DC-Stark spectra under weak DC electric fields, we find that the measurement accuracy of the former is significantly superior to that of the latter.

This work makes use of a Cs atomic vapor cell with an integrated electrode to avoid shielding effects. By observing Floquet-EIT spectra, the response of the spectra to DC electric fields is investigated. This experiment provides novel insights into the quantum sensing measurements of DC and low-frequency electric fields.