Classical Capacity of Arbitrarily Distributed Noisy Quantum Channels

TL;DR

This paper investigates the maximum rate at which classical information can be reliably transmitted over quantum channels affected by both classical and quantum noise, providing a foundational understanding for quantum communication networks.

Contribution

It introduces a novel analysis of mixed classical-quantum noise effects on arbitrary quantum channels and derives the achievable capacity considering such noise.

Findings

Capacity increases with the number of photons per usage.

Derived the distribution of mixed noise from a classical perspective.

Formulated the achievable channel capacity under mixed noise conditions.

Abstract

With the rapid deployment of quantum computers and quantum satellites, there is a pressing need to design and deploy quantum and hybrid classical-quantum networks capable of exchanging classical information. In this context, we conduct the foundational study on the impact of a mixture of classical and quantum noise on an arbitrary quantum channel carrying classical information. The rationale behind considering such mixed noise is that quantum noise can arise from different entanglement and discord in quantum transmission scenarios, like different memories and repeater technologies, while classical noise can arise from the coexistence with the classical signal. Towards this end, we derive the distribution of the mixed noise from a classical system's perspective, and formulate the achievable channel capacity over an arbitrary distributed quantum channel in presence of the mixed noise. Numerical results demonstrate that capacity increases with the increase in the number of photons per usage.