RT Journal Article
SR Electronic
T1 Experimental test of local observer independence
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaaw9832
DO 10.1126/sciadv.aaw9832
VO 5
IS 9
A1 Proietti, Massimiliano
A1 Pickston, Alexander
A1 Graffitti, Francesco
A1 Barrow, Peter
A1 Kundys, Dmytro
A1 Branciard, Cyril
A1 Ringbauer, Martin
A1 Fedrizzi, Alessandro
YR 2019
UL http://advances.sciencemag.org/content/5/9/eaaw9832.abstract
AB The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them. In quantum mechanics the objectivity of observations is not so clear, most markedly exposed in Wigner’s eponymous thought experiment where two observers can experience seemingly different realities. The question whether the observers’ narratives can be reconciled has only recently been made accessible to empirical investigation, through recent no-go theorems that construct an extended Wigner’s friend scenario with four observers. In a state-of-the-art six-photon experiment, we realize this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by five standard deviations. If one holds fast to the assumptions of locality and free choice, this result implies that quantum theory should be interpreted in an observer-dependent way.