Do entangled particles lose entanglement after polarizing filters?

Question

If two entangled particles are sent through different polarizing filters, do they lose their entanglement after the filters?

Answer 1

Yes. A polarizing filter absorbs the wave polarized orthogonally to the polarization direction of the polarizer. Assume that the particles are photons in the polarization singlet,

|Singlet> = (1/sqrt(2)) {|x>|x> + |y>|y>}.

For simplicity let x be the direction of polarization transmitted by the filter for one of the particles. You see that in the entanglement appear both the x-polarization and the y-polarization. But the filter absorbs the polarization y.

That doesn't mean that all the photons impinging on the above filter get x-polarized and get out of the filter. No, for the above singlet, the filter absorbs half of the incoming photons.

You may have more questions, as the result of this answer, but I answered here ONLY to the present question.

Good luck !