On the learnability of quantum state fidelity Norhan Elsayed Amer, Walid Gomaa, Keiji Kimura, Kazunori Ueda and Ahmed El-Mahdy EPJ Quantum Technol., 9 1 (2022) 31 Published online: 20 November 2022 DOI: 10.1140/epjqt/s40507-022-00149-8