Enhanced and reduced absorptions via quantum interference: Solid system driven by a rf field

We observed quantum interference effects in steady-state optical absorption in a V-type three-level system of Pr³⁺:YAlO₃ where a hyperfine transition between two upper levels was homogeneously broadened by pure dephasing. This V-type system was excited by a single driving radio-frequency (rf) field and two probe laser fields (quantum-beat scheme). The probe absorption was constructively or destructively affected by the phase of the driving rf field. In contrast, under two-laser excitation without application of the rf, no absorption change due to electromagnetically induced transparency (EIT) was observed. A comparison of observations and theoretical predictions revealed that the quantum-beat scheme generates quantum interference even when the dephasing rate between the two upper levels is comparable with the Rabi frequency of the probe laser, and completely destroys EIT.