  Capabilities of quantum optical SFG-gate seeded by squeezed light are
investigated in the frame of frequency Schmidt modes. Methods to manage and
manipulate extensively the properties and mode content of squeezed light are
developed. Possibilities to block and select any certain Schmidt mode of
squeezed light with conservation of non-classical properties are demonstrated.
The significant phase sensitivity of the gate is shown and the ways to manage
the spectral distribution of the output light due to the phase effects and
variable coupling between modes in the gate are demonstrated. The effect of
swapping between modes in the gate is found. It allows to enhance squeezed
light in a set of modes without loss of photon correlations which is important
for further experiments and new applications.

Quantum Physics