Master thesis: High-rate multipartite quantum secret sharing with continuous variables

TL;DR

This thesis introduces a high-rate multipartite quantum secret sharing protocol using continuous variables, enabling secure multi-user communication with practical optical components, advancing quantum cryptography's scalability and efficiency.

Contribution

It presents a novel metropolitan-scale continuous-variable quantum cryptography protocol for multipartite secret sharing with potential for high-rate secure communication.

Findings

Protocol allows multiple users to share secure keys via a relay.

Uses generalised Bell detection for creating multipartite correlations.

Potential for high-rate secure communication with existing optical technology.

Abstract

Quantum cryptography has undergone substantial growth and development within the multi-disciplinary field of quantum information in recent years. The field is constantly advancing with new protocols being developed, security measures being improved, and the first practical applications of these technologies being deployed in optical fibers and free space optical beams. In this paper, we present a comprehensive review of a cutting-edge metropolitan-scale protocol for continuous-variable quantum cryptography. The protocol allows an arbitrary number of users to send modulated coherent states to a relay, where a generalised Bell detection creates secure multipartite correlations. These correlations are then distilled into a shared secret key, providing a secure method for quantum secret-sharing. This novel approach to quantum cryptography has the potential to offer high-rate secure multipartite communication using readily available optical components, making it a promising advancement in the field.