COLLECTIVE EFFECTS IN THE MICROLASER

In a microlaser experiment performed by An et al. with collaborators [ Phys. Rev. Lett. 73, 3375 (1994)] an atomic beam interacts with a micr ocavity field under such conditions that the average number of atoms i n the cavity is less than unity. However, due to the random statistics of atoms in the beam, the probability of two atoms being in the cavit y simultaneously in time is not negligible. This must lead to collecti ve two-atom effects that are not included in the standard microlaser m odel. We have developed a theory that incorporates such collective eff ects. This theory allows a better understanding of the observed experi mental results and predicts some different features of the microlaser.