Cooperative two-photon interaction with nonclassical light

The two-photon interaction process of N identical three-level atoms with squeezed light is considered. The dependence of the absorption process on the squeezed fluctuations of light is studied. It is shown that the absorption rate of phase squeezed light is larger than the absorption rate of amplitude squeezed light. If the amplitude of the fluctuations is approximately equal to the average value of the electromagnetic field intensity, the quantum fluctuations can stop the two-photon nutation in the system. The possibility of a first-order phase transition in the system composed by the atoms and the external electromagnetic field is discussed.