Amending coherence-breaking channels via unitary operations

TL;DR

This paper investigates how to modify coherence-breaking quantum channels using unitary operations, providing conditions for identifying and amending such channels, especially focusing on qubit channels.

Contribution

It introduces necessary and sufficient conditions for coherence-breaking channels and proposes a method to amend them via unitary operations, including for non-coherence-breaking qubit channels.

Findings

Derived conditions for coherence-breaking channels

Proposed a method to amend channels with unitary operations

Analyzed coherence-breaking properties of qubit channels

Abstract

The coherence-breaking channels play a significant role in quantum information theory. We study the coherence-breaking channels and give a method to amend the coherence-breaking channels by applying unitary operations. For given incoherent channel $\Phi$, we give necessary and sufficient conditions for the channel to be a coherence-breaking channel and amend it via unitary operations. For qubit incoherent channels $\Phi$ that are not coherence-breaking ones, we consider the mapping $\Phi\circ\Phi$ and present the conditions for coherence-breaking and channel amendment as well.