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When scientists entangle photons or atoms or other objects, is it only their state that gets entangled? What about their proximity in space? If you move one sideways will you see the other one move sideways as well?

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In general, entanglement of two objects is not necessarily connected to spatial proximity. Entanglement means that you need to consider both particles' quantum states when you want to describe the properties of the system. You cannot describe an entangled particle's quantum state independently of the other one.

There is no restriction as to which properties can be correlated. It could be spin, polarization, or even position. But even if the particles are entangled with respect to their position - that does not mean that you can control one by manipulating the other. It means that if you measure the position of one particle (i.e. "look at it"), the position of the other one will be known as well. At this point, the entangled state brakes down. The particles are no longer entangled when you perform the measurement and the positions are known.

So to wrap it up, let's move through your questions: Yes, it is their states that are entangled. Spatial position can be correlated, too. No, you will not see one particle move because of the other due to entanglement.

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  • $\begingroup$ So if we were to entangle a particle on the moon and 1, say here on earth. The spin imparted on the particle by the moon, due to its orbit around earth, rotation own axis and around our star wouldnt neccesarily have an affect on its twin here on earth? Allowing us to harness the power of the moons orbit? $\endgroup$ – Ngubane Johannes Senzesihle May 15 '18 at 12:54
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    $\begingroup$ No it wouldn't. You could just measure the spin of the particle on earth and gain information about the spin of the particle on the moon. And when you have the information about the quantum state, you lose the entanglement. $\endgroup$ – lmr May 15 '18 at 13:00
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    $\begingroup$ Further to @lmr's comment: the crux of entanglement in the case of particles whose positions are entangled, is that we can never see a particle move or jump from one place to another per your question because that would require "before and after" measurements of the particle's position, and the "before" measurement will have already determined the positions of both particles. $\endgroup$ – S. McGrew May 15 '18 at 13:56

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