Capacities of lossy bosonic channel with correlated noise

TL;DR

This paper analyzes the classical capacity of a lossy bosonic channel with correlated noise, demonstrating that entangled input states and global encoding/decoding schemes outperform local ones when memory effects are present.

Contribution

It introduces a model with correlated noise in bosonic channels and shows that global encoding/decoding schemes with entanglement optimize capacity under memory effects.

Findings

Global schemes outperform local ones with memory effects.

Analytical expression for classical capacity in certain parameter ranges.

Results applicable to a broad class of bosonic Gaussian channels.

Abstract

We evaluate the information capacities of a lossy bosonic channel with correlated noise. The model generalizes the one recently discussed in [Phys. Rev. A 77, 052324 (2008)], where memory effects come from the interaction with correlated environments. Environmental correlations are quantified by a multimode squeezing parameter, which vanishes in the memoryless limit. We show that a global encoding/decoding scheme, which involves input entangled states among different channel uses, is always preferable with respect to a local one in the presence of memory. Moreover, in a certain range of the parameters, we provide an analytical expression for the classical capacity of the channel showing that a global encoding/decoding scheme allows to attain it. All the results can be applied to a broad class of bosonic Gaussian channels.