u/Double-Agent77

Reposted from r/Physics as they decided to remove my post because its "related to homework". If anyone can think of a homework assignment that would involve quantum entanglement and high level quantum thought experiments like Wheelers delayed choice, I'd be surprised!

Long story short: Is it possible to devise an experiment to determine whether a particle is in a superposition of spin states at a given time, in the same way that the double slit experiment forces particles to either form an interference pattern because they travelled through both slits, or else act like particles that only travelled through one slit.

If this is possible, and it can be done in such a way that an entangled particle is the one that is either observed or not to collapse the wave function, then the distant person running this experiment could determine whether the setup at the other end is observing or not observing the particles.

This gets around the whole "forcing particles into a particular state" issue because we're instead looking at the possible conditions of being or not being in a superposition state at a given time, where we already have the double slit experiment that can distinguish between these two cases in terms of their positional information given enough particles.

Interested to hear thoughts!!

I'm under no illusions that the following experiment would actually work, I'd just be interested to see if anyone can come up with a good explanation for why.

Take 1000 pairs of entangled electron pairs, or any particle where we can create entangled pairs really. Take one sent of pairs to a distant location and prepare a double slit style experiment where you prepare to send the particles through to observe the interference pattern.

The experiment here is what happens if the other particles are measured at the exact time when their partners are transitioning through the double slit experiment? This is effectively an experimdnt to determine if we can tell if the particles are in a superposition or not when they pass through. In the normal double slit we measured the particle position which causes the wave function to collapse and the interference pattern (generated by sending many particles) is replaced by two peaks. If this can be done instead with entangled particles some distance away, then the information "measured" or "not measured" can surely be transferred from one location to the other?

This gets around the whole "forcing particles into a particular state" issue because we're instead looking at the possible conditions of being or not being in a superposition state at a given time, where we already have the double slit experiment that can distinguish between these two cases given enough particles.

Interested to hear thoughts!!