Nonlinear photon subtraction from a multimode quantum field.

We consider theoretically how to extract mode-dependent single photons from a time and frequency multimode nonclassical beam. To achieve this task, we calculate the properties of sum frequency generation with a pulse shaped pump, taking into account both temporal and spatial degrees of freedom. We show that using a noncollinear configuration it is possible to achieve a mode-dependent weakly reflective beam splitter, with Schmidt number compatible with photon extraction for continuous variable regime tasks. We make explicit the possible application to the degaussification of highly multimode squeezed frequency combs. [ABSTRACT FROM AUTHOR]