Quantum Cloning without Interference

Abstract

We study the role of interference in the process of quantum cloning. We show that in order to achieve better than classical cloning of a qubit no interference is needed. In particular, a large class of symmetric universal 1$\to$ 2 qubit cloners exists which achieve the optimal average fidelity 5/6 for such machines, without using any interference. We also obtain optimal average fidelities for interference--free cloning in asymmetric situations, and discuss the relation of the quantum cloners found to the Bužek--Hillery quantum cloner.

14 pages revtex, 1 eps figure

References in corpus (3)

• Role of interference in quantum state transfer through spin chains
• Distribution of interference in random quantum algorithms
• Interference versus success probability in quantum algorithms with imperfections

Cited by in corpus (3)

• Quantum Cloning Machines and the Applications
• A universal set of qubit quantum channels
• Distribution of Interference in the Presence of Decoherence