Cloning of single photon by high gain amplifier

Abstract

In the last years the simultaneous realization of the optimal cloning and optimal flipping of an input qubit has been reported adopting a quantum injected optical parametric amplifier. The previous process spreads the quantum information contained in the initial qubit into a three qubits state in an universal and optimal way. In the present chapter the previous results are extended to a large number of qubits. The successful generation of a multiparticle quantum superposition of photon states by a universal cloning of a single photon qubit amplified by a high gain parametric amplifier is reported. The information preserving property of the process suggests for these states the name of multi-particle qubits. They are ideal objects for investigating the emergence of the classical world in quantum systems with increasing complexity, the decoherence processes and may allow the practical implementation of the universal two-qubit logic gates. © 2006 Springer Science+Business Media, Inc.