Optimal Measurement Basis for Economical Phase-covariant Telecloning with Partially Entangled States

Recently, Wang and Yang (Phys. Rev. A 79:062315, 2009) presented a scheme for economical phase-covariant telecloning of qubits with W-class entangled states. For realizing probabilistically the suboptimal telecloning in the case that the sender's subsystem and the receivers' subsystem are partially entangled, they introduced a special two-qubit measurement basis. I here study the effects of the sender's different measurements on the fidelity of the clones in such a scheme, and obtain several interesting results. The most important result is that Bell-basis is the optimal measurement basis in terms of the average fidelity of the clones, although the special-basis measurement can lead to the suboptimal fidelity with a certain probability.