As I read in this question: If two particles are entangled and you collapse the wave function of one of the particles. Does the other particle collapse as well? Two entangled particles share the same wave function that describes the entire quantum system. My question is, if you think in the individual particles, say A and B, is it OK to think that B = F(A) where F would be the "correlation" between the two?


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In quantum mechanics if two particles are entangled you can't talk about the state of each of them individually. Objects in quantum mechanics are described by vectors in a Hilbert space, and using bra-ket notation we have an entangled state as follows:

$$\left | \Psi \right>_{AB} = \frac 1 {\sqrt 2} \left ( \left | 0 \right>_A \left|0\right>_B+\left | 1 \right>_A \left|1\right>_B\right)$$

A state is not entangled if and only if you can write it as a "product state":

$$\left| \Psi \right>_{AB}= \left| \psi\right>_A \left|\phi\right>_B$$

Only in this case can you talk about the state of a single subsystem (or particle).


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