  We observed squeezed vacuum light at 795 nm in 87Rb vapor via resonant
polarization self-rotation, and report noise sidebands suppression of ~1 dB
below shot noise level spanning from acoustic (30 kHz) to MHz frequencies. This
is the first demonstration of sub-MHz quadrature vacuum squeezing in atomic
systems. The spectral range of observed squeezing matches well typical
bandwidths of electromagnetically induced transparency (EIT) resonances, making
this simple technique for generation of optical fields with non-classical
statistics at atomic transitions wavelengths attractive for EIT-based quantum
information protocols applications.
