There is an opinion that experiments with delayed choice quantum eraser cannot be emulated by classical methods. However, this opinion is not true.
Let's conduct the following thought experiment:
imagine that in the direction of Alice and Bob, whose laboratories are located
at a distance in space, not pairs of particles are launched, but pairs of macroscopic
arrows at different random angles in a certain plane (YZ). All participants in
the experiment know in advance that each pair is launched at the same angle to
the Z-axis, but if we take many pairs of launched pairs, the angles are
randomly distributed between the pairs of arrows. It is also known that if one
arrow in a pair is directed with its nose in one direction, then the other - in
strictly opposite direction.
The registration of arriving arrows in each space
laboratory is as follows: at the edge of a circular hole in the plane (YZ) in
the spacecraft of Alice and Bob, which are distant from each other, through
which the arrows fly, there is a registration sensor directed to the center of
the hole. He knows how to register the 'nose' or 'tail' of the arrow. If the
arrow is turned towards it with the nose at least at a small angle, the arrow
sensor registers the 'nose'. If on the contrary, then the 'tail'. For clarity,
we can assume that there are red lights on the 'noses', and green ones on the 'tails',
and only one of the two lights is visible to the detector.
In the diagram, the holes in the walls of the space
laboratories of Alice and Bob are superimposed on one another. During the
experiment, a strict arrangement of these holes in parallel planes is
maintained. Alice's and Bob's pointers for registering arrows are mutually
located as shown in the diagram: at an angle φ.