"Assisted cloning'' and "orthogonal-complementing" of an unknown state

Abstract

We propose a protocol where one can exploit dual quantum and classical channels to achieve perfect ``cloning'' and ``orthogonal-complementing'' of an unknown state with a minimal assistance from a state preparer (without revealing what the input state is). The first stage of the protocol requires usual teleportation and in the second stage, the preparer disentangles the left-over entangled states by a single particle measurement process and communicates a number of classical bits (1-cbit per copy) to different parties so that perfect copies and complement copies are produced. We discuss our protocol for producing two copies and three copies (and complement copies) using two and four particle entangled state and suggest how to generalise this for N copies and complement copies using multiparticle entangled state.