Experimental Test of Local Observer-Independence Using IBM’s Quantum Computer

Abstract: The precise interpretation of quantum mechanics is still open to discussion. A number of non-intercompatible interpretations, with a not unsignificant respective following, are at the time of writing still viable. When Eugene Wigner stated his titular thought experiment he managed to highlight how varying assumptions and accompanying mechanisms can have implications even on a macro-scale. Caslav Brukner expands the thought experiment of Wigner's Friend in his recent paper and derives a theorem using the setup. In our paper, we empirically validate the theorem derived in Brukner's paper, employing a setup based on his extended Wigner's Friend experiment. More precisely, we realise this setup on a 5-qubit Quantum Computer and achieve a violation of a Bell-type inequality, close to what is theoretically possible. This seems to imply that local observer-independent facts are not possible within the current framework of quantum mechanics.