Robust Self-Testing of Multiparticle Entanglement
Dian Wu, Qi Zhao, Xuemei Gu, Han-Sen Zhong, You Zhou, Li-Chao Peng, Jian Qin, Yi-Han Luo, Kai Chen, Li Li, Nai-Le Liu, Chao‐Yang Lu, Jian-Wei Pan · Physical Review Letters · 2021
Quantum self-testing is a device-independent way to certify quantum states and measurements using only the input-output statistics, with minimal assumptions about the quantum devices. Because of the high demand on tolerable noise, however, experimental self-testing was limited to two-photon systems. Here, we demonstrate the first robust self-testing for multiphoton genuinely entangled quantum states. We prepare two examples of four-photon graph states, the Greenberger-Horne-Zeilinger states with a fidelity of 0.957(2) and the linear cluster states with a fidelity of 0.945(2). Based on the observed input-output statistics, we certify the genuine four-photon entanglement and further estimate their qualities with respect to realistic noise in a device-independent manner.