Optical nonlinearities of excitonic self-induced-transparency solitons: Toward ultimate realization of squeezed states and quantum nondemolition measurement

Self-induced transparency in a resonant two-level system creates a 2π-soliton pulse, which produces large optical nonlinearities with a very fast response time and an extremely small loss. The self-phase modulation of a 2π soliton and the mutual-phase modulation by the collision of two 2π solitons in the excitonic range of the spectrum in CdS can achieve the effective ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$ coefficient of ${10}^{\mathrm{-}6}$ to ${10}^{\mathrm{-}4.5}$ esu for a pulse duration of 1 to 3 ps. The quantum theory of 2π solitons predicts this new nonlinear process can realize squeezed states and quantum nondemolition measurement 20 dB below the standard quantum limit.