Resonant Multilevel Amplitude Damping Channels

TL;DR

This paper introduces resonant multilevel amplitude damping (ReMAD) channels, a new quantum channel class modeling energy dissipation in multilevel atomic systems, with exact capacity calculations in various parameter regions.

Contribution

The paper defines ReMAD channels, characterizes their algebraic properties, and analyzes their quantum and private classical capacities, including cases where they are neither degradable nor antidegradable.

Findings

ReMAD channels can model energy dissipation in multilevel systems.

Capacities are exactly computed in broad parameter regions.

ReMAD channels exhibit degradability and antidegradability in large parameter spaces.

Abstract

We introduce a new set of quantum channels: resonant multilevel amplitude damping (ReMAD) channels. Among other instances, they can describe energy dissipation effects in multilevel atomic systems induced by the interaction with a zero-temperature bosonic environment. At variance with the already known class of multilevel amplitude damping (MAD) channels, this new class of maps allows the presence of an environment unable to discriminate transitions with identical energy gaps. After characterizing the algebra of their composition rules, by analyzing the qutrit case, we show that this new set of channels can exhibit degradability and antidegradability in vast regions of the allowed parameter space. There we compute their quantum capacity and private classical capacity. We show that these capacities can be computed exactly also in regions of the parameter space where the channels aren't degradable nor antidegradable.