Quasi-Superactivation of Classical Capacity of Zero-Capacity Quantum Channels

TL;DR

This paper demonstrates that zero-capacity quantum channels can achieve nonzero classical capacity through a process called quasi-superactivation, challenging previous assumptions and expanding quantum communication possibilities.

Contribution

It introduces the concept of quasi-superactivation for classical capacity, showing that zero-capacity channels can be activated with simple photon-atom interactions.

Findings

Nonzero classical capacity achieved for all zero-capacity channels

Stimulated emission enables quasi-superactivation

Challenges previous beliefs about classical capacity limitations

Abstract

One of the most surprising recent results in quantum Shannon theory is the superactivation of the quantum capacity of a quantum channel. This phenomenon has its roots in the extreme violation of additivity of the channel capacity and enables to reliably transmit quantum information over zero-capacity quantum channels. In this work we demonstrate a similar effect for the classical capacity of a quantum channel which previously was thought to be impossible. We show that a nonzero classical capacity can be achieved for all zero-capacity quantum channels and it only requires the assistance of an elementary photon-atom interaction process - the stimulated emission.