  We report the generation of a squeezed vacuum state of light whose noise
ellipse rotates as a function of the detection frequency. The squeezed state is
generated via a four-wave mixing process in a vapor of 85Rb. We observe that
rotation varies with experimental parameters such as pump power and laser
detunings. We use a theoretical model based on the Heisenberg-Langevin
formalism to describe this effect. Our model can be used to investigate the
parameter space and to tailor the ellipse rotation in order to obtain an
optimum squeezing angle, for example, for coupling to an interferometer whose
optimal noise quadrature varies with frequency.
