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arXiv · 2010.02904

Generalized Measure of Quantum Fisher Information

Akira Sone·M. Cerezo·Jacob L. Beckey·Patrick J. Coles
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Abstract

In this work, we present a lower bound on the quantum Fisher information (QFI) which is efficiently computable on near-term quantum devices. This bound itself is of interest, as we show that it satisfies the canonical criteria of a QFI measure. Specifically, it is essentially a QFI measure for subnormalized states, and hence it generalizes the standard QFI in this sense. Our bound employs the generalized fidelity applied to a truncated state, which is constructed via the $m$ largest eigenvalues and their corresponding eigenvectors of the probe quantum state $\rho_{\theta}$. Focusing on unitary families of exact states, we analyze the properties of our proposed lower bound, and demonstrate its utility for efficiently estimating the QFI.

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Akira Sone, M. Cerezo, Jacob L. Beckey, Patrick J. Coles. 2020-10-06. Generalized Measure of Quantum Fisher Information. https://doi.org/10.1103/physreva.104.062602

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