It would sure be a lot better to actually describe the experiment. From your picture I'm guessing that two photons are generated from one source (closest to the viewer, black box) which then bounce off mirrors to Alice and Bob. So it's not surprising that they are anti correlated.
The surprise is that the correlation is stronger than you can explain with classical theory. That's what Einstein in 1933 was worried about. Link to the experiment: www.quantenspiegelungen.de/en/subdimension-line-u1/entangled-photons/experiments-with-entangled-photons/
It would sure be a lot better to actually describe the experiment.
From your picture I'm guessing that two photons are generated from one source (closest to the viewer, black box) which then bounce off mirrors to Alice and Bob. So it's not surprising that they are anti correlated.
The surprise is that the correlation is stronger than you can explain with classical theory. That's what Einstein in 1933 was worried about. Link to the experiment: www.quantenspiegelungen.de/en/subdimension-line-u1/entangled-photons/experiments-with-entangled-photons/