Squeezed light enhanced polarization interferometer.

Enhancement of the sensitivity of a polarization interferometer beyond the limit set by vacuum fluctuations of the electromagnetic field has been been obtained using squeezed light generated by a KTiOPO sub 4 optical parametric amplifier. The increase in signal-to-noise ratio relative to the shot-noise limit is 2 db. The corresponding improvement in the response time of the interferometer is measured to be a factor of 1.6.