Pulsed quadrature-phase squeezing of solitary waves in x „2... parametric waveguides

It is shown that coherent quantum simultons ~simultaneous solitary waves at two different frequencies! can undergo quadrature-phase squeezing as they propagate through a dispersive x (2) waveguide. This requires a treatment of the coupled quantized fields including a quantized depleted pump field. A technique involving nonlinear stochastic parabolic partial differential equations using a nondiagonal coherent state representation in combination with an exact Wigner representation on a reduced phase space is outlined. We explicitly demonstrate that group-velocity matched x (2) waveguides which exhibit collinear propagation can produce quadrature-phase squeezed simultons. Quasi-phase-matched KTP waveguides, even with their large groupvelocity mismatch between fundamental and second harmonic at 425 nm, can produce 3 dB squeezed bright pulses at 850 nm in the large phase-mismatch regime. This can be improved to more than 6 dB by using group-velocity matched waveguides. @S1050-2947~97!06707-3#