Generalized measure of quantum Fisher information

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