Optimality of the asymmetric economical phase-covariant quantum cloning
Quantum cloning can be reviewed as the optimal individual eavesdropping on quantum cryptography. Specifically, the optimal phase-covariant cloning is regarded as the optimal individual attack on the BB84 protocol. In this paper, by exploring Cerf's formalism, we prove the optimality of the asymmetric economical 1→2 phase-covariant quantum cloning in 2 dimensions working without ancilla. In proof, we derive another independent unitary transformation of this cloner. Our result covers previous contributions [Durt T, et al. Phys. Rev. A, 2004, 69: 062316].
国家科技期刊平台
NSTL
万方数据
维普
