Quantum erasure experiment and delay selection experiment are more advanced versions of double slit experiment, which can demonstrate more characteristics of quantum mechanics.

Quantum erasure experiment demonstrates that the interference pattern generated by wave behavior can be recovered by erasing path information. The experiment has three steps:

Irradiate the particle beam on an opaque plate engraved with two slits, and then confirm that the interference pattern appears on the detection screen.

Observe which slit the particle passes through. When observing, you must be careful not to excessively disturb the movement of photons, and then confirm that the interference pattern displayed on the detection screen has been destroyed. This step demonstrates that the interference pattern is destroyed because it is possible to obtain path information.

Through the special program, the path information can be erased, but the interference pattern can also be obtained again.

The delay selection experiment demonstrates that after the particles arrive at the detection screen, the interference pattern can be recovered or destroyed by erasing or marking the path information. This time gap relationship can even be extended to a very long time in theory. If the path information is marked, the particle only passes through one path; If the path information is erased, the particle passes through two paths at the same time. This means that the behavior of the observer can determine what happened in the past, and this conclusion is contrary to the traditional view of reality.