Squeezed Light

Spontaneous parametric down-conversion (SPDC) converts a pump beam into pairs of correlated photons known as the signal and idler. These correlations can manifest in various ways, one of which is squeezed light, where the quantum uncertainty of one quadrature of the electric field is reduced (“squeezed”), while simultaneously increasing the uncertainty in the other quadrature  (“anti-squeezed” or “stretched”).