Incomplete quantum process tomography and principle of maximal entropy

TL;DR

This paper extends the maximum entropy principle to incomplete quantum process tomography by defining a process entropy based on the von Neumann entropy, providing a unified framework for quantum process estimation.

Contribution

It introduces a process entropy function for quantum process estimation and demonstrates its consistency and reduction to state MaxEnt in special cases.

Findings

Unified framework for quantum process estimation using MaxEnt

Process entropy satisfies natural properties

Reduces to state MaxEnt for preparator devices

Abstract

The main goal of this paper is to extend and apply the principle of maximum entropy (MaxEnt) to incomplete quantum process estimation tasks. We will define a so-called process entropy function being the von Neumann entropy of the state associated with the quantum process via Choi-Jamiolkowski isomorphism. It will be shown that an arbitrary process estimation experiment can be reformulated in a unified framework and MaxEnt principle can be consistently exploited. We will argue that the suggested choice for the process entropy satisfies natural list of properties and it reduces to the state MaxEnt principle, if applied to preparator devices.