Quantum Channel Capacities

TL;DR

This paper reviews the different capacities of quantum channels for transmitting classical, private, and quantum information, discussing known results, additivity issues, and future research directions.

Contribution

It provides a comprehensive summary of quantum channel capacities and highlights open problems and potential research avenues.

Findings

Summarizes known capacities of quantum channels.

Discusses additivity questions in quantum information theory.

Suggests directions for future research in quantum communication.

Abstract

A quantum communication channel can be put to many uses: it can transmit classical information, private classical information, or quantum information. It can be used alone, with shared entanglement, or together with other channels. For each of these settings there is a capacity that quantifies a channel's potential for communication. In this short review, I summarize what is known about the various capacities of a quantum channel, including a discussion of the relevant additivity questions. I also give some indication of potentially interesting directions for future research.