parametric down conversion造句

However, after the slits, spontaneous parametric down conversion ( SPDC ) is used to prepare an entangled two-photon state.
At the same time the nonlinear process of parametric down conversion began to be utilised and from then until the present day it has become the workhorse of experiments requiring single photons.
It's difficult to find parametric down conversion in a sentence. 用parametric down conversion造句挺难的