LIMITS TO SQUEEZING AND PHASE INFORMATION IN THE PARAMETRIC-
AMPLIFIER
P. Kinsler, M. Fernee, P.D. Drummond.
Department of Physics
University of Queensland
Queensland 4072
Australia
Phys. Rev. A 48, 3310, (1993).
We investigate the time evolution of squeezing in the signal mode
of the undamped parametric amplifier. Both the degenerate and
nondegenerate cases are considered. These are the simplest models
that give limits to squeezing caused by both the intrinsic pump
noise and pump depletion. Conflicting analytic expressions have
been reported. We resolve this by the use of exact numerical
methods, employing both number state and stochastic techniques.
Our central result is that in both cases we find that the minimum
in the squeezed quadrature variance scales as N-1/2BAR, where NBAR
is the initial coherent pump photon number. This bound on the
amount of squeezing obtainable, coupled with the loss in energy
due to the conversion efficiency, serves to limit the phase
information in the squeezed channel to no more than that of the
coherent pump. We believe this to be a fundamental limit for
using the squeezed radiation generated in coherently driven
parametric amplifiers.
Email: Dr.Paul.Kinsler@physics.org