Multiple quantum entanglements

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Discussion Overview

The discussion centers around the nature of quantum entanglement, specifically whether multiple particles can be entangled simultaneously in a non-binary manner. Participants explore the implications of entanglement involving three particles and the conditions under which such entanglement occurs.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant questions if multiple systems can be entangled simultaneously or if entanglement must remain binary.
  • Another participant asserts that entanglement can involve more than two particles, suggesting that A, B, and C can form a single entangled system, but observing one particle alters the state of the others.
  • A different viewpoint argues that entanglement cannot occur between A/B and A/C simultaneously, mentioning the GHZ state as a less effective form of entanglement.
  • Another participant challenges the previous claims, stating that photons B and C would be in a definite state unless entangled with other photons, and discusses the concept of entanglement swapping as a potential mechanism for creating new entangled states.

Areas of Agreement / Disagreement

Participants express differing views on the nature of entanglement involving multiple particles, with no consensus reached on whether simultaneous entanglement is possible or how it should be characterized.

Contextual Notes

Participants reference various states of entanglement and the effects of measurement on entangled systems, but the discussion includes unresolved assumptions about the nature of entanglement and the specific conditions required for different states.

serp777
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Lets say you have a particle A, which then physically interacts with particle C and B to become entangled. Since A is entangled with B, and C is entangled with A, then it would follow that c is entangled to B. I guess my main question is it possible to have multiple systems entangled with each other simultaneously, or does it have to be binary? And my next question is if its possible, then is C technically entangled to B, even though they are entangled through A?
 
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serp777 said:
Lets say you have a particle A, which then physically interacts with particle C and B to become entangled. Since A is entangled with B, and C is entangled with A, then it would follow that c is entangled to B. I guess my main question is it possible to have multiple systems entangled with each other simultaneously, or does it have to be binary? And my next question is if its possible, then is C technically entangled to B, even though they are entangled through A?

You can have entanglement of more than 2 particles, there is no real absolute upper limit other that practical ones due to decoherence. So A, B and C form an entangled system and you would not say that A and B are entangled and A and C are entangled. On the other hand, if you observe the spin of A, then you throw B and C into a different entangled state (2 particles instead of 3).
 
serp777 said:
Lets say you have a particle A, which then physically interacts with particle C and B to become entangled. Since A is entangled with B, and C is entangled with A, then it would follow that c is entangled to B. I guess my main question is it possible to have multiple systems entangled with each other simultaneously, or does it have to be binary? And my next question is if its possible, then is C technically entangled to B, even though they are entangled through A?
You can't have entanglement between A/B and A/C at the same time. You can have so called GHZ state but it gives less "entanglement per photon" figuratively speaking. Basically you detect one of the three photons and then from that result you can find out what type of correlation you should expect for other two photons.

As a loose analogy we could use this - single equation with two unknowns (entanglement) and single equation with three unknowns (GHZ state).
 
serp777 said:
Lets say you have a particle A, which then physically interacts with particle C and B to become entangled. Since A is entangled with B, and C is entangled with A, then it would follow that c is entangled to B. I guess my main question is it possible to have multiple systems entangled with each other simultaneously, or does it have to be binary? And my next question is if its possible, then is C technically entangled to B, even though they are entangled through A?

I don't think that works. Photons B and C would be in a definite state (unless they're entangled with other photons). Interaction between B and A wouldn't cause entanglement in this case, so far as what I've been told by Markus Arndt.

Perhaps if B and C were entangled, and A was entangled with another photon D the best you can get from interaction between B (or C) and A is an entanglement swap. This would create entanglement between D and B (or C), and A and C (or B).
 

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