Quantum beats in the field ionization of Rydberg atoms in the presence of magnetic fields*

By exciting a coherent superposition and varying its phase evolution, quantum beats in the selective field ionization of Rydberg atoms have been observed [R. Feynman, et al., \textit{PRA}, \textbf{92}, 043412 (2015)]. Here, we present a study exploring the effect of electric and magnetic fields on quantum beats. Beginning with a single excited state, a coherent superposition is created by a short electric field pulse in the presence of a static magnetic field. The resulting quantum beats are then observed in the field ionization spectrum. Additionally, millimeter-wave spectroscopy is used to probe the state populations in this superposition.