Question about the "Unitary Operation" in Teleportation How is the unitary operation actually performed in quantum teleportation(by Bob)? I can never seem to find a thorough explaination of this when I look up teleportation in the literature or on the internet. I understand that Bob's particle is in an unentangled state described by a single qubit pure state, but that it has to be transformed(via a unitary operation) to the original state of Alice's qubit. If you look at it in a real experimental picture, Bob not only has to transform the particle, but he has to distinguish the specific particle which requires the transformation. This means identifying one particle in a whole beam(like a needle in a haystack) and then perform the unitary operation exclusively on it. How is this accomplished? Is Bob somehow able to separate the four possible teleported states without having recieved the classical message from Alice or does he need to wait for the transmission before he even identifies the correct particle?