Quantum Teleportation of N qubits with perfect fidelity using maximally entangled states is explained. It is shown that non-maximally entangled states are used the minimum assured fidelity decreases. It is explained how the success 1/2 of teleportation of a superposition of even and odd coherent states suggested by Van Enk and Hirota was modified by Prakash, Chandra, Prakash and Shivani. It is also shown that the decrease in entanglement may sometimes even result in increase in fidelity. so as to make the success nearly 1. It is also explained how decoherence can be taken into account and how such schemes can be applied to similar phenomena of entanglement diversion and entanglement swapping.
Polarized photons have properties that can be explained, among others, by their indistinguishability. This includes superposition and entanglement. We propose that the superposition state can be understood as the entirety of all mixtures of indistinguishable perpendicularly polarized photon beams. The photon beams, whose polarization correspond to the position of the polarizer, are filtered out by selection using a polarizer. There are no nonlocal effects with the entangled photons. This is because the physical states of the photons are defined before each measurement. The model replicates the predictions of quantum mechanics for entangled photons and also explains entanglement swapping and teleportation. The superposition of indistinguishable photon beams can be experimentally demonstrated using a Mach-Zehnder interferometer. This explains how the polarization of the input state reappears at the output of the Mach-Zehnder interferometer.