%0 Journal Article %D 2022 %T Self-Testing of a Single Quantum System: Theory and Experiment %A Hu, Xiao-Min %A Xie, Yi %A Arora, Atul Singh %A Ai, Ming-Zhong %A Bharti, Kishor %A Zhang, Jie %A Wu, Wei %A Chen, Ping-Xing %A Cui, Jin-Ming %A Liu, Bi-Heng %A Huang, Yun-Feng %A Li, Chuan-Feng %A Guo, Guang-Can %A Roland, Jérémie %A Cabello, Adán %A Kwek, Leong-Chuan %K Atomic Physics (physics.atom-ph) %K FOS: Physical sciences %K Quantum Physics (quant-ph) %X

Certifying individual quantum devices with minimal assumptions is crucial for the development of quantum technologies. Here, we investigate how to leverage single-system contextuality to realize self-testing. We develop a robust self-testing protocol based on the simplest contextuality witness for the simplest contextual quantum system, the Klyachko-Can-Binicioğlu-Shumovsky (KCBS) inequality for the qutrit. We establish a lower bound on the fidelity of the state and the measurements (to an ideal configuration) as a function of the value of the witness under a pragmatic assumption on the measurements we call the KCBS orthogonality condition. We apply the method in an experiment with randomly chosen measurements on a single trapped 40Ca+ and near-perfect detection efficiency. The observed statistics allow us to self-test the system and provide the first experimental demonstration of quantum self-testing of a single system. Further, we quantify and report that deviations from our assumptions are minimal, an aspect previously overlooked by contextuality experiments.

%8 3/17/2022 %G eng %U https://arxiv.org/abs/2203.09003 %R https://doi.org/10.48550/arXiv.2203.09003