In a way, entanglement is inevitable if you superposition is possible. For example: imagine particle decayed into two other particles. For conservation of mome

In a way, entanglement is inevitable if you superposition is possible. For example: imagine particle decayed into two other particles. For conservation of momentum to hold, those two particles must go in opposite direction. So if you measure direction of one particle, you instantly know direction of the other one. Otherwise you would vitness universe in invalid state.