Teleportation: from probability distributions to quantum states

The role of the off-diagonal density-matrix elements of the entangled pair is investigated in the quantum teleportation of a qubit. The dependence bet ween these elements and the off-diagonal elements of the teleported density matrix is shown to be linear. In this way ideal quantum teleportation is r elated to a completely classical communication protocol: the one-time pad c ypher. The latter can be regarded as the classical counterpart of Bennett's quantum-teleportation. scheme. The quantum-to-classical transition is demo nstrated by a gedankenexperiment.