Quantum process capability

Chung-Cheng Kuo,He Lu,Che-Ming Li,Hung-Ming Chen,Shih-Hsuan Chen,Wei-Ting Lee

doi:10.1038/s41598-019-56751-x

Chung-Cheng Kuo, He Lu + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-56751-x

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Abstract

Physical processes in the quantum regime possess non-classical properties of quantum mechanics. However, methods for quantitatively identifying such processes are still lacking. Accordingly, in this study, we develop a framework for characterizing and quantifying the ability of processes to cause quantum-mechanical effects on physical systems. We start by introducing a new concept, referred to as quantum process capability, to evaluate the effects of an experimental process upon a prescribed quantum specification. Various methods are then introduced for measuring such a capability. It is shown that the methods are adapted to quantum process tomography for implementation of process capability measure and applicable to all physical processes that can be described using the general theory of quantum operations. The utility of the proposed framework is demonstrated through several examples, including processes of entanglement, coherence, and superposition. The formalism proposed in this study provides a generic approach for the identification of dynamical processes in quantum mechanics and facilitates the general classification of quantum-information processing.

Highlights

Physical processes in the quantum regime possess non-classical properties of quantum mechanics
To place the basic definitions of capable and incapable processes into a wider context, we introduce a measurable property of a process called the quantum process capability, which provides a quantitative understanding of how well χexpt might work, and helps identify processes with prescribed quantum process abilities
We provide an explicit example illustrating how a dynamical process of interest can be identified upon the prescribed quantum specification (i.e., E1–E4)

Summary

Introduction

Physical processes in the quantum regime possess non-classical properties of quantum mechanics. In this study, we develop a framework for characterizing and quantifying the ability of processes to cause quantum-mechanical effects on physical systems. Despite the success of theoretical methods in describing the dynamics of quantum systems, such as the quantum operations formalism[3], the problem of characterizing the prescribed quantum-mechanical features of dynamical processes in a quantitatively precise manner has yet to be resolved. We introduce two capability measures and a task-oriented capability criterion, which demonstrate that such process evaluation can be quantitatively determined through experimentally feasible means. We show that with the proposed tools, it is possible, for the first time, to quantitatively identify several fundamental types of dynamical process, including processes of entanglement, coherence and superposition

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