  We theoretically evaluate the squeezed joint operators produced in a single
optical parametric oscillator which generates quadripartite entangled outputs,
as demonstrated experimentally by Pysher et al. \cite{pysher}[Phys. Rev. Lett.
107, 030505 (2011)]. Using a linearized fluctuation analysis we calculate the
squeezing of the joint quadrature operators below threshold for a range of
local oscillator phases and frequencies. These results add to the existing
theoretical understanding of this potentially important system.
