Non-Markovianity and reservoir memory of quantum channels: a quantum information theory perspective

TLDR

Quantum technologies depend on coherent state transfer through channels, but environmental decoherence limits their efficiency, and longer channels generally reduce capacity. The study introduces a theoretical framework linking non‑Markovianity to quantum channel capacities and shows how exploiting memory effects can enhance information processing and communication. The authors develop a general theoretical framework that relates non‑Markovianity to channel capacities and illustrate its application to improve quantum communication efficiency. For non‑Markovian channels, the capacity of a longer channel can exceed that of a shorter one, contrary to the Markovian case.

Abstract

Quantum technologies rely on the ability to coherently transfer information encoded in quantum states along quantum channels. Decoherence induced by the environment sets limits on the efficiency of any quantum-enhanced protocol. Generally, the longer a quantum channel is the worse its capacity is. We show that for non-Markovian quantum channels this is not always true: surprisingly the capacity of a longer channel can be greater than of a shorter one. We introduce a general theoretical framework linking non-Markovianity to the capacities of quantum channels and demonstrate how harnessing non-Markovianity may improve the efficiency of quantum information processing and communication.