Quantum interference with different polarization

[gespex]

Hi all,

Imagine a double slit experiment where each slit contains a polarization filter with some angle relative to each other ([itex]\alpha[/itex]). If the polarization filters are parallel the usual interference pattern will emerge, and when they are perpendicular no interference pattern will emerge. What happens when they have different relative angles, though?
The problem is that I've read two different sources, Wikipedia states:

The two waves must have the same polarization to give rise to interference fringes since it is not possible for waves of different polarizations to cancel one another out or add together. Instead, when waves of different polarization are added together, they give rise to a wave of a different polarization state.

While someone answered a question saying that it did interfere and that the intensity would be:
[tex]I=I_1+I_2+2\sqrt{I_1I_2}cos(\alpha)[/tex]

It claims that there are still the same interference pattern, but it simply gets closer to no interference.

So which is right?Thanks in advance

 

[Simon Bridge]

Do you have a reference for the second answer?
Also see: http://arxiv.org/pdf/1110.4309.pdf
p8 ... the argument is that the components that are aligned in polarity interfere.