Interacting double dark resonances in a tripod system of room-temperature⁴He

Abstract

We experimentally study two different tripod configurations using metastable 4 He, with the probe perpendicular and parallel to the quantization axis, defined by an applied weak magnetic field. In the first case, the two dark resonances interact incoherently and merge together into a single transparency peak with increasing coupling power. In the second case, we observe destructively interfering double dark resonances leading to a narrow absorption dip at the line center. We confirm the results theoretically.