Coherent preorder of quantum states

TL;DR

This paper characterizes the structure of quantum coherence preorders under strongly incoherent operations and proposes methods for coherence distillation and manipulation between rank-two mixed states.

Contribution

It provides a structural characterization of coherent preorder under strongly incoherent operations and introduces new schemes for coherence distillation and manipulation.

Findings

Structural characterization of coherent preorder provided.

Proposed approach for coherence distillation from rank-two states.

Presented scheme for coherence manipulation between rank-two states.

Abstract

As an important quantum resource, quantum coherence play key role in quantum information processing. It is often concerned with manipulation of families of quantum states rather than individual states in isolation. Given two pairs of coherent states $(\rho_1,\rho_2)$ and $(\sigma_1,\sigma_2)$, we are aimed to study how can we determine if there exists a strictly incoherent operation $\Phi$ such that $\Phi(\rho_i) =\sigma_i,i = 1,2$. This is also a classic question in quantum hypothesis testing. In this note, structural characterization of coherent preorder under strongly incoherent operations is provided. Basing on the characterization, we propose an approach to realize coherence distillation from rank-two mixed coherent states to $q$-level maximally coherent states. In addition, one scheme of coherence manipulation between rank-two mixed states is also presented.