  We report the observation of multiple laser thresholds in the many-atom
cavity QED microlaser. Traveling-wave coupling and a supersonic atom beam are
used to create a well-defined atom-cavity interaction. Multiple thresholds are
observed as jumps in photon number due to oscillatory gain. Although the number
of intra-cavity atoms is large, up to N~1000, the dynamics of the microlaser
agree with a single atom theory. This agreement is supported by quantum
trajectory simulations of a many-atom microlaser and a semiclassical microlaser
theory. We discuss the relation of the microlaser with the micromaser and
conventional lasers.
