Quantum Cloning Machines and the Applications

TL;DR

This paper reviews the development, types, and applications of quantum cloning machines, emphasizing their role in quantum information security and the progress made in theoretical and experimental studies.

Contribution

It provides a comprehensive, self-contained overview of quantum cloning machines, including detailed formulations for further research and application insights.

Findings

Various quantum cloning machines have been designed for different quantum protocols.

Quantum cloning machines are crucial for analyzing quantum key distribution security.

Significant progress has been made in both theoretical and experimental studies of quantum cloning.

Abstract

No-cloning theorem is fundamental for quantum mechanics and for quantum information science that states an unknown quantum state cannot be cloned perfectly. However, we can try to clone a quantum state approximately with the optimal fidelity, or instead, we can try to clone it perfectly with the largest probability. Thus various quantum cloning machines have been designed for different quantum information protocols. Specifically, quantum cloning machines can be designed to analyze the security of quantum key distribution protocols such as BB84 protocol, six-state protocol, B92 protocol and their generalizations. Some well-known quantum cloning machines include universal quantum cloning machine, phase-covariant cloning machine, the asymmetric quantum cloning machine and the probabilistic quantum cloning machine etc. In the past years, much progress has been made in studying quantum cloning machines and their applications and implementations, both theoretically and experimentally. In this review, we will give a complete description of those important developments about quantum cloning and some related topics. On the other hand, this review is self-consistent, and in particular, we try to present some detailed formulations so that further study can be taken based on those results.