[evanb]

You're very close to understanding to quantum eraser experiment / the even more upsetting delayed-choice quantum eraser.

Even though it sounds as though your arguments are gotchas that prove quantum mechanics to be nonsense, it turns out the world really is that way.

https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser

[graycat]

Gee, I'm not the first to make this mistake about quantum mechanics!