Exploring Fringe Visibility from Entropy of Two-Level Particles

[Heidi]

i consider a pair of two level particles which can be up or down. this pair is described in the
tensor product by the unitary vector $$(cos(\theta) (du + ud) + sin(\theta) (dd + u)) /\sqrt 2$$
i take its density matrix , trace it on one of the two particles and find the density matrix
of each one. And i calculate its entropy. Bob receive it and use the two slits device.
I wonder if i can deduce the fringe visibility on the screen from the calculated entropy.
thank you for your help.

 

[Heidi]

Here
https://www.researchgate.net/post/How_can_I_measure_the_contrast_of_a_fringe_pattern
some one recalls the definition of fringe visibility
(Imax-Imin)/(Imax+Imin)
Anothe one writes
visibility = amplitude/average
where average of the fringes is the sum of the intensities (or powers) of the two interfering waves
Could you explain that?

 

[Heidi]

Could anyone tell me if the fringe visibility can be found from the
density matrix or from the vector in the tensor product of Hilbert spaces? Is there a book or a link about this subject?
thanks.