Table 1.

A list of contributing SFWM processes (left column) to corresponding signal-idler polarization states (right column).

SFWM processes	Signal-idler state
HHHH and HHVV	HH
VVVV and VVHH	VV
HVHV and HVVH	HV
VHHV and VHVH	VH

The first, second, third, and forth letters specify polarization states of the signal, idler, first pump, and second pump photons.