Superfluorescence is reported from an initially inverted, pure two-level system. Single-pulse emission occurs at low densities; neither homogeneous relaxation nor inhomogeneous dephasing nor linear diffraction can explain the absence of ringing. At higher densities multiple-pulse outputs occur. The experimental results are not in good quantitative agreement with present theories.

• Received 16 May 1977

DOI:https://doi.org/10.1103/PhysRevLett.39.547