Limitations to squeezing in a parametric amplifier due to pump quantum fluctuations
David D. Crouch, Samuel L. Braunstein · Physical Review A · 1988
We perform discrete-mode calculations for a parametric amplifier with a quantum pump and discuss some of the limitations on calculations of this sort in quantum optics. We calculate corrections to the squeezing due to pump quantum fluctuations to order N${\ifmmode\bar\else\textasciimacron\fi{}}^{\mathrm{\ensuremath{-}}2}$, for a pump initially in a coherent state with average photon number N\ifmmode\bar\else\textasciimacron\fi{}. We find that the limit to the variance of the squeezed quadrature due to the quantum nature of the pump goes as N${\ifmmode\bar\else\textasciimacron\fi{}}^{\mathrm{\ensuremath{-}}1/2}$. .AE