Unitary-invariant method for witnessing nonstabilizerness in quantum processors
Rafael Wagner, Filipa C. R. Peres, Emmanuel Zambrini Cruzeiro, Ernesto F. Galvão · Journal of Physics A Mathematical and Theoretical · 2025
Abstract Nonstabilizerness, also known as ‘magic’, is a crucial resource for quantum computation. The growth in complexity of quantum processing units (QPUs) demands robust and scalable techniques for characterizing this resource. We introduce the basis-independent notion of set magic: a set of states has this property if at least one state in the set is a magic state. We show that certain two-state overlap inequalities, recently introduced as witnesses of basis-independent coherence, are also witnesses of set magic. Finally, we show that using such witnesses one can robustly certify nonstabilizerness in a network of QPUs without having to entangle the different devices and with reduced demands compared to the individual certification of each QPU.