Figure 4

(a) Rydberg state \(|50S_{1/2}\rangle \) AC Stark shift \(\Delta _{l}\) fitted to electric field. (b)Measured enhancement factor versus microwave field frequency. (c)EIT spectra of the Rydberg state \(|50S_{1/2}\rangle \) acquired without microwave field (black curve), with an applied 2 GHz 0.5 dBm microwave field and resonator (red curve) and with an applied 2 GHz 25 dBm microwave field (blue curve). The figure shows red and blue curve have same AC shift \(\Delta _{l}\) of about 4.24 MHz. (d)Normalized electric-field polarization response by rotating the antenna, the error bars representing the standard deviation