Optimal Broadcasting of Mixed Equatorial Qubits
Zong‐Wen Yu · Chinese Physics Letters · 2009
We derive an optimal 2 → M phase-covariant quantum broadcasting of mixed equatorial qubits. This quantum broadcasting is optimal in the sense that the shrinking factor between the input and the output single qubit achieves the upper bound. The result shows that we can copy two identical mixed equatorial qubits with the same quality as those of two identical pure equatorial states.