Information trade-offs for optical quantum communication

TL;DR

This paper explores the fundamental limits and advantages of trade-off coding in optical quantum communication, demonstrating significant performance gains over traditional methods for various bosonic channels.

Contribution

It provides a detailed analysis of the achievable trade-offs in quantum communication tasks and shows practical benefits of trade-off coding for bosonic channels.

Findings

Trade-off coding outperforms time-sharing in several bosonic channels.

Significant performance gains are observed in free-space, fiber-optic, and thermal-noise channels.

Trade-offs between public and private classical information transmission are advantageous.

Abstract

Recent work has precisely characterized the achievable trade-offs between three key information processing tasks---classical communication (generation or consumption), quantum communication (generation or consumption), and shared entanglement (distribution or consumption), measured in bits, qubits, and ebits per channel use, respectively. Slices and corner points of this three-dimensional region reduce to well-known protocols for quantum channels. A trade-off coding technique can attain any point in the region and can outperform time-sharing between the best-known protocols for accomplishing each information processing task by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space / fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels.