Raman-noise limit on squeezing in continuous-wave four-wave mixing.

The continuous-time quantum theory of self-phase modulation (SPM) in lossless, dispersionless, single-mode fiber requires a nonzero response time, to capture the classical SPM limit properly, and an accompanying Raman noise, to ensure commutator preservation. The continuous-wave, four-wave mixing limit of this theory is shown to harbor a Raman-noise limit on fiber-based squeezed-state generation.