Universal Quantum Cloning Machines for Two Identical Mixed Qubits

• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2007,（11）
• 页码范围: 3048-3050
• 页数: 3页
• 语种: 英文

摘要

We present a series of universal quantum cloning machines for two identical mixed qubits. Every machine is optimal in the sense that it achieves the optimal bound of the single copy shrinking factor. Unlike in the case of pure state cloning, the single copy shrinking factor does not uniquely determine the cloning map in the case of mixed state cloning.