  We propose a method of producing steady-state coherent light with negative
Wigner functions in nonlinear media combined with feedback control. While the
nonlinearities are essential to produce the Wigner negativities, this alone is
insufficient to stabilize steady-state light with negativities. Using feedback
control to control the phase in the cavity, we find that this produces
significant total negativities for reasonable experimental parameters. The
negative Wigner function is produced continuously and does not appear to be
restricted to low-amplitude light. The technique is applicable to systems such
as exciton-polaritons, where strong natural nonlinearities are present.
