quantum non-locality Werner states correlation particles quantum state hidden variables
In the media and popular science, quantum non-locality is often portrayed as being equivalent to entanglement. While this is true for pure bipartite quantum states, in general entanglement is only necessary for non-local correlations, but there exist mixed entangled states that do not produce such correlations. A well-known example is the Werner states that are entangled for certain values of 




p

s
y
m




{\displaystyle p_{sym}}

, but can always be described using local hidden variables. Moreover, it was shown that, for arbitrary numbers of particles, there exist states that are genuinely entangled but admit a local model.
