Abstract

The nonclassical nature of the so-called squeezed states of electromagnetic fields has recently been discussed in connection with the phenomenon of resonance fluorescence from a coherently driven two-level atom.¹ It has been shown that either the in-phase component E₁ or the out-of-phase component E₂ of the fluorescent field can become squeezed if the Rabi frequency Ω of the ex- citing field is sufficiently low. Squeezing is defined as a negative value of the normally ordered variance 〈: (ΔE₁)²:〉 (or 〈:(ΔE₂)²:〈). To satisfy this condition in the steady state, if the exciting field is tuned perfectly to the atomic transition, the Rabi frequency Ω has to be less than √2y, with 2y = A—the Einstein coefficient for spontaneous emission. Off-resonance excitation further lowers this critical value of 0. Walls and Zoller¹ have indicated, without giving the details, that, in a transient regime, the squeezing effect can become twice as large as in the steady state.

© 1984 Optical Society of America