Multi-field quantum conferencing overcomes the network capacity limit

TL;DR

This paper introduces a practical multi-field quantum conferencing scheme that surpasses the fundamental rate-distance limit, enabling scalable, secure group communication in quantum networks using existing experimental techniques.

Contribution

It proposes a novel, measurement-device-independent scheme utilizing post-measurement coincidence matching to overcome the rate limit without quantum repeaters.

Findings

The scheme can support any number of users.

Simulations show it surpasses the fundamental rate-distance limit.

Supports long-distance quantum broadcast communication.

Abstract

Quantum conferencing enables multiple nodes within a quantum network to share a secure group key for private message broadcasting. The key rate, however, is limited by the repeaterless capacity to distribute multiparticle entangled states across the network. Currently, in the finite-size regime, no feasible schemes utilizing existing experimental techniques can overcome the fundamental rate-distance limit of quantum conferencing in quantum networks without repeaters. Here, we propose a practical, multi-field scheme that breaks this limit, involving virtually establishing Greenberger-Horne-Zeilinger states through post-measurement coincidence matching. This proposal features a measurement-device-independent characteristic and can directly scale to support any number of users. Simulations show that the fundamental limitation on the group key rate can be overcome in a reasonable running time of sending $10^{14}$ pulses. We predict that it offers an efficient design for long-distance broadcast communication in future quantum networks.