Bob cannot become entangled with the outside world while in the middle of a quantum erasure experiment, or else it doesn't work. So he doesn't really get to do anything :P
If Bob knows that the particle becomes entangled with him, then he still makes the same predictions.
If Bob knows that the particle becomes entangled with him, then he still makes the same predictions.
Ok, that's surprising. Here's why I thought otherwise: From Bob's perspective, a particle is prepared in a superposition of states B and C. Then Bob observes or becomes entangled with the particle, thus collapsing its state. Then the super-duper quantum erasure is performed, which preserves the state of the particle. Then the particle strikes the second half-silvered mirror. A collapse interpretation tells Bob to expect two outcomes with equal probability. Is this, then, an experiment where a collapse interpretation and a many-worlds interpretation give different predictions?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Duration set to six days to encourage Monday as first day.