What is Possible Without Disturbing Quantum Signals
Masato Koashi, Nobuyuki Imoto · arXiv (Cornell University) · 2001
Consider a situation in which a quantum system is secretly prepared in a state chosen from the known set of n states. We show that the fundamental properties of classical and quantum signals lead to a principle that gives a definite distinction between the operations that preserve the states of the system and those that do not. Many types of no-cloning and no-imprinting conditions can easily be derived from this principle. The principle also gives a unified view on how various schemes of quantum cryptography work.