15 January 2025

Title: Metrological usefulness of entanglement and nonlinear Hamiltonians

Speaker: Dr. Satoya Imai, QSTAR, INO-CNR, and LENS, Florence, Italy

Abstract of Talk:A central task in quantum metrology is to exploit quantum correlations to outperform classical sensitivity limits. Metrologically useful entanglement is identified when the quantum Fisher information (QFI) exceeds a separability bound for a given parameter-encoding Hamiltonian. However, so far, only results for linear Hamiltonians are well-established.

Here, we characterize metrologically useful entanglement for nonlinear Hamiltonians, presenting separability bounds for collective angular momenta. Also, we provide a general expression for entangled states maximizing the QFI, showing that these can be the superposition between the GHZ and singlet states. Finally, we compare the metrological usefulness of linear and nonlinear cases. Reference: https://arxiv.org/abs/2405.15703

Profile of Speaker: https://sites.google.com/view/satoyaimai/home