Quantum Cloning of Binary Coherent States - Optimal Transformations and Practical Limits

TL;DR

This paper explores the theoretical limits and practical methods for optimally cloning binary coherent states, bridging the formalisms of qubits and coherent states to analyze cloning fidelities.

Contribution

It introduces a formal connection between qubit and coherent state cloning, analyzing optimal and near-optimal cloning schemes for binary coherent states.

Findings

Comparison of cloning fidelities for different schemes

Identification of practical cloning methods close to optimal performance

Analysis of the formal connection between qubit and coherent state cloning

Abstract

The notions of qubits and coherent states correspond to different physical systems and are described by specific formalisms. Qubits are associated with a two-dimensional Hilbert space and can be illustrated on the Bloch sphere. In contrast, the underlying Hilbert space of coherent states is infinite-dimensional and the states are typically represented in phase space. For the particular case of binary coherent state alphabets these otherwise distinct formalisms can equally be applied. We capitalize this formal connection to analyse the properties of optimally cloned binary coherent states. Several practical and near-optimal cloning schemes are discussed and the associated fidelities are compared to the performance of the optimal cloner.