  The output field from a continuously driven linear parametric oscillator may
exhibit considerably more squeezing than the intracavity field. Inspired by
this fact, we explore the nonclassical features of the steady-state output
field of a driven nonlinear Kerr parametric oscillator using a temporal wave
packet mode description. Utilizing a new numerical method, we have access to
the density matrix of arbitrary wave packet modes. Remarkably, we find that
even though the steady-state cavity field is always characterized by a positive
Wigner function, the output may exhibit Wigner negativity, depending on the
properties of the selected mode.

Quantum Physics