Verification of quantum-domain process using two non-orthogonal states

TL;DR

This paper presents a simple method to verify whether a quantum process genuinely operates in the quantum domain by using two non-orthogonal states, with applications to quantum communication and storage.

Contribution

The authors introduce a straightforward scheme to verify quantum-domain processes using only two non-orthogonal states, enhancing practical quantum channel validation.

Findings

The scheme effectively distinguishes quantum channels from measure-and-prepare schemes.

Application examples include quantum optical coherent states and single-photon polarization states.

The method provides a practical tool for experimental quantum information tasks.

Abstract

If a quantum channel or process cannot be described by any measure-and-prepare scheme, we may say the channel is in \textit{quantum domain} (QD) since it can transmit quantum correlations. The concept of QD clarifies the role of quantum channel in quantum information theory based on the local-operation-and-classical-communication (LOCC) paradigm: The quantum channel is only useful if it cannot be simulated by LOCC. We construct a simple scheme to verify that a given physical process or channel is in QD by using two non-orthogonal states. We also consider the application for the experiments such as the transmission or storage of quantum optical coherent states, single-photon polarization states, and squeezed vacuum states.