If we use a double-slit experiment with a which-path detector, and have an observer try to remember (or forget) which slit each photon passed through, why can't we use the resulting pattern—interference or not—as a readout of the observer’s memory state?<p>If no one remembers the which-path info, we expect interference. If someone does remember, the pattern should collapse to two bands. Why hasn't this been tested as a method to probe the interaction between human memory and quantum measurement? Feels related to Wigner’s friend, but focused on the memory-retention threshold.<p>Is this experimentally viable?
My understanding is that the wave function will collapse if information can be retrieved, so the moment it <i>can be known</i> which slit it goes through, it's already over.<p>I also have a fun QM experiment idea but I could be wildly misinformed:<p>You make two experiments, one where you fire polarized photons at a screen and one where you fire non-polarized photons. You come back some time later (irrelevant but who cares), and decide using a cosmic radiation detector (radiation still coming to us from the big bang, so truly non-deterministic) which screen to choose. You fire a regular photon and the two slits. My understanding is that if the polarized screen is chosen, the photon will come through as a particle and if not, as a wave.