In the double slit experiment, If there was an electromagnetic field at the slits, would the electron still create an interference pattern? Or would the presence of the field collapse the wave function of the electron?
Let's start from a generic, unspecified "detector". When a detector is on, the wave function collapses. What counts as a detector? ANY interaction capable of discriminating between which of the two slits the particle went through. So if an electromagnetic could conceivably identify which slit the particle went through, then the wave function collapses. If the interaction with the electromagnetic field cannot reveal that information (if there is an interaction, but it is not relevant to the "which slit?" issue), then the wave function doesn't collapse and there is an interference pattern on the screen.