Quantum Beats in Superfluorescence in Atomic Cesium

Superfluorescence has been observed at 3 μm on the $7P$-to-$7S$ transition in atomic cesium after 2-ns excitation of a $6S$-to-$7P$ transition. Both in a magnetic field and in zero field, quantum beats have been observed. The beat frequencies correspond not only to initial-level splittings but also to combinations of initial- and final-level splittings. Superfluorescence beats are therefore basically different from single-atom quantum beats.