  When linearly polarized light propagates through a medium in which
elliptically polarized light would undergo self-rotation, squeezed vacuum can
appear in the orthogonal polarization. A simple relationship between
self-rotation and the degree of vacuum squeezing is developed. Taking into
account absorption, we find the optimum conditions for squeezing in any medium
that can produce self-rotation. We then find analytic expressions for the
amount of vacuum squeezing produced by an atomic vapor when light is
near-resonant with a transition between various low-angular-momentum states.
Finally, we consider a gas of multi-level Rb atoms, and analyze squeezing for
light tuned near the D-lines under realistic conditions.
