Channel coding against quantum jammers via minimax

TL;DR

This paper introduces a minimax method to analyze the capacities of fully quantum arbitrarily varying channels, showing that certain capacities match those of compound channels even with quantum adversaries, without complex reductions.

Contribution

The paper presents a novel minimax approach that simplifies capacity analysis of quantum channels under adversarial conditions, avoiding de Finetti reductions and dimension dependencies.

Findings

Entanglement-assisted capacities match those of compound channels.

Shared-randomness-assisted capacities are equivalent to those of compound channels.

Method simplifies analysis of quantum channels with adversaries.

Abstract

We introduce a minimax approach for characterizing the capacities of fully quantum arbitrarily varying channels (FQAVCs) under different shared resource models. In contrast to previous methods, our technique avoids de Finetti-type reductions, providing a more streamlined proof without dependency on the dimension of the jamming system. Consequently, we show that the entanglement-assisted and shared-randomness-assisted capacities of FQAVCs match those of the corresponding compound channels, even in the presence of general quantum adversaries.