An ideal nondegenerate parametric oscillator is known to give perfect squeezing in the difference of the intensities of the signal and idler modes. In this paper, we look at a frequency down-conversion system comprising three-level atoms in a cavity. The squeezing in the intensity difference is calculated and found, in general, to be degraded by spontaneous emission. In the limit of large detunings, the system is found to behave as a nondegenerate parametric oscillator.

• Received 6 December 1990

DOI:https://doi.org/10.1103/PhysRevA.43.5049