Quantum Fisher Information: Variational principle and simple iterative algorithm for its efficient computation

TL;DR

This paper introduces a new variational approach and an iterative algorithm for efficiently computing quantum Fisher information, with proofs of convergence and discussion of classical Fisher information cases.

Contribution

It presents a novel variational principle and a simple iterative algorithm for quantum Fisher information computation, including convergence proof and classical case analysis.

Findings

New variational principle for quantum Fisher information

An iterative algorithm with proven convergence

Discussion of classical Fisher information case

Abstract

We derive a new variational principle for the quantum Fisher information leading to a simple iterative alternating algorithm, the convergence of which is proved. The case of a fixed measurement, i.e. the classical Fisher information, is also discussed.