How to Maximize the Capacity of General Quantum Noisy Channels

TL;DR

This paper investigates how to maximize the capacity of general quantum noisy channels by optimizing basis selection and temporal shaping, considering symmetry-breaking decoherence, memory effects, and noise bias.

Contribution

It introduces a novel approach to optimize quantum channel capacity through basis selection and temporal shaping, accounting for complex noise characteristics.

Findings

Optimal basis is a mix of factorized and partially-entangled states.

Capacity maximization involves temporal shaping and basis optimization.

The approach accounts for asymmetry, memory, and bias in noise.

Abstract

A general quantum noisy channel is analyzed, wherein the transmitted qubits may experience symmetry-breaking decoherence, along with memory effects. We find the optimal basis not to be fully entangled, but a combination of factorized and partially-entangled states in the presence of memory, asymmetry and the state-bias of the noise. Capacity-maximization is shown to be achievable by combining temporal shaping of the transmitted qubits and optimal basis selection.