Scalable implementation of ancilla-free optimal 1 → M phase-covariant quantum cloning by combining quantum Zeno dynamics and adiabatic passage

A scalable way for implementation of ancilla-free optimal 1 -> M phase-covariant quantum cloning (PCC) is proposed by combining quantum Zeno dynamics and adiabatic passage. An optimal 1 -> M PCC can be achieved directly from the existed optimal 1 -> (M - 1) PCC without excited states population during the whole process. The cases for optimal 1 -> 3 (4) PCCs are discussed detailedly to show that the scheme is robust against the effect of decoherence. Moreover, the time for carrying out each cloning transformation is regular, which may reduce the complexity for achieving the optimal PCC in experiment. (C) 2011 Elsevier B.V. All rights reserved.