Quantum noise reduction in stationary superradiance

We discuss a laser with N three-level atoms resonantly and cooperatively interacting with two cavity modes. Its intensity is proportional to N², the linewidth scales as 1/N², and the output intensity fluctuations display up to 100% squeezing at low frequencies. We show that quantum fluctuations of the pump do not deteriorate the squeezing significantly. We also find that the fluctuation properties of the ‘‘passive’’ cavity mode which serves to collectively relax the atoms to the ground state are similar to those of the active mode. Finally we take into account spontaneous emission. Within a certain range of frequencies good squeezing can still be found. © 1996 The American Physical Society.