2020/10/31 by Jacob L. Beckey, M. Cerezo, Akira Sone +1 · 1 citation
Computer Science · Mathematics · Physics and Astronomy · #Algorithm #Computer science #Fisher information #Mathematics #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum algorithm #Quantum mechanics #Quantum-Dot Cellular Automata #Statistical physics #Statistics #physics.data-an #quant-ph
paper · pdf · doi:10.1103/physrevresearch.4.013083
published as Phys. Rev. Research 4, 013083 (2022) · v2: significantly revised manuscript according to peer reviews
arxiv created 2022/01/04 · openalex publication_date 2022/02/02 · arxiv updated 2022/02/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
The quantum Fisher information (QFI) quantifies the ultimate precision of estimating a parameter from a quantum state and can be regarded as a reliability measure of a quantum system as a quantum sensor. However, estimation of the QFI for a mixed state is in general a computationally demanding task. In this paper we present a variational quantum algorithm called variational quantum Fisher information estimation (VQFIE) to address this task. By estimating lower and upper bounds on the QFI, based on bounding the fidelity, VQFIE outputs a range in which the actual QFI lies. This result can then be used to variationally prepare the state that maximizes the QFI, for the application of quantum sensing. In contrast to previous approaches, VQFIE does not require knowledge of the explicit form of the sensor dynamics. We simulate the algorithm for a magnetometry setup and demonstrate the tightening of our bounds as the state purity increases. For this example, we compare our bounds with literature bounds and show that our bounds are tighter.