Self-testing of a single quantum system from theory to experiment

Research Projects
Organizational Units
Journal Issue
Self-testing allows one to characterise quantum systems under minimal assumptions. However, existing schemes rely on quantum nonlocality and cannot be applied to systems that are not entangled. Here, we introduce a robust method that achieves self-testing of individual systems by taking advantage of contextuality. The scheme is based on the simplest contextuality witness for the simplest contextual quantum system—the Klyachko-Can-Binicioğlu-Shumovsky inequality for the qutrit. We establish a lower bound on the fidelity of the state and the measurements as a function of the value of the witness under a pragmatic assumption on the measurements. We apply the method in an experiment on a single trapped 40Ca+ using randomly chosen measurements and perfect detection efficiency. Using the observed statistics, we obtain an experimental demonstration of self-testing of a single quantum system.
Hu, X.-M., Xie, Y., Atul Singh Arora, Ai, M.-Z., Kishor Bharti, Zhang, J., Wu, W., Chen, P.-X., Cui, J.-M., Liu, B.-H., Huang, Y.-F., Li, C.-F., Guo, G.-C., Roland, J., Cabello, A., & Kwek, L.-C. (2023). Self-testing of a single quantum system from theory to experiment. Npj Quantum Information, 9(1), Article 103.