Quantum null-hypothesis device-independent Schmidt number witness Josep Batle, Tomasz Białecki, Tomasz Rybotycki, Jakub Tworzydło and Adam Bednorz EPJ Quantum Technol., 11 1 (2024) 62 Published online: 27 September 2024 DOI: 10.1140/epjqt/s40507-024-00273-7