Optical squeezed vacuum
= Optical squeezed vacuum
A single optical mode in a <squeezed vacuum state>. In principal <optical quadratures>, its variances are $e^{-2r}/4$ and $e^{2r}/4$, while its mean <photon> number is $\sinh^2r$. Its mean field vanishes. A degenerate <optical parametric amplifier> generates the state by pair creation with phase fixed by the pump. Loss admixes unsqueezed vacuum and limits the measured variance reduction.