Directed quantum communication

TL;DR

This paper explores how quantum information transfer differs from classical transfer, emphasizing the need for directed signals and sufficient collection of quantum signals, with a focus on medium properties and scaling laws.

Contribution

It introduces a framework for characterizing quantum communication in media, highlighting the importance of directionality and signal collection thresholds.

Findings

Quantum communication requires directed signals unlike classical transfer.

A threshold exists for signal collection to enable quantum communication.

Scaling laws for medium size relative to transmission distance are derived.

Abstract

We raise the question whether there is a way to characterize the quantum information transport properties of a medium or material. For this analysis the special features of quantum information have to be taken into account. We find that quantum communication over an isotropic medium, as opposed to classical information transfer, requires the transmitter to direct the signal towards the receiver. Furthermore, for large classes of media there is a threshold, in the sense that `sufficiently much' of the signal has to be collected. Therefore, the medium's capacity for quantum communication can be characterized in terms of how the size of the transmitter and receiver has to scale with the transmission distance to maintain quantum information transmission. To demonstrate the applicability of this concept, an n-dimensional spin lattice is considered, yielding a sufficient scaling of d^(n/3) with the distance d.