General bounds for sender-receiver capacities in multipoint quantum communications

TL;DR

This paper establishes fundamental bounds on the capacities for quantum information transmission, entanglement distillation, and secret key distribution in complex multipoint quantum communication networks with unlimited classical assistance.

Contribution

It provides the first comprehensive bounds for multipoint quantum communication scenarios, including broadcast, multiple-access, and general networks, applicable to various physical systems.

Findings

Derived bounds for quantum broadcast channels.

Derived bounds for quantum multiple-access channels.

Unified bounds applicable to arbitrary-dimensional quantum systems.

Abstract

We investigate the maximum rates for transmitting quantum information, distilling entanglement, and distributing secret keys between a sender and a receiver in a multipoint communication scenario, with the assistance of unlimited two-way classical communication involving all parties. First we consider the case where a sender communicates with an arbitrary number of receivers, so called quantum broadcast channel. Here we also provide a simple analysis in the bosonic setting where we consider quantum broadcasting through a sequence of beamsplitters. Then, we consider the opposite case where an arbitrary number of senders communicate with a single receiver, so called quantum multiple-access channel. Finally, we study the general case of all-in-all quantum communication where an arbitrary number of senders communicate with an arbitrary number of receivers. Since our bounds are formulated for quantum systems of arbitrary dimension, they can be applied to many different physical scenarios involving multipoint quantum communication.