Gaussian bosonic synergy: quantum communication via realistic channels of zero quantum capacity

TL;DR

This paper demonstrates that certain pairs of zero-capacity optical quantum channels can be combined to achieve positive quantum capacity, revealing a superactivation effect in realistic noisy environments, with implications for quantum communication.

Contribution

It extends the superactivation phenomenon to practical Gaussian optical channels, highlighting potential for experimental realization and improved quantum communication strategies.

Findings

Superactivation occurs in Gaussian optical channels with attenuation and noise.

Pairs of zero-capacity channels can achieve positive capacity when combined.

Results suggest new avenues for quantum communication in realistic settings.

Abstract

As with classical information, error-correcting codes enable reliable transmission of quantum information through noisy or lossy channels. In contrast to the classical theory, imperfect quantum channels exhibit a strong kind of synergy: there exist pairs of discrete memoryless quantum channels, each of zero quantum capacity, which acquire positive quantum capacity when used together. Here we show that this "superactivation" phenomenon also occurs in the more realistic setting of optical channels with attenuation and Gaussian noise. This paves the way for its experimental realization and application in real-world communications systems.