Southwest Quantum Information and Technology

Chained Bell inequality experiment with high-efficiency measurements

Presenting Author: Yong Wan, NIST
Contributing Author(s): T. R. Tan, S. Erickson, P. Bierhorst, D. Kienzler, S. Glancy, E. Knill, D. Leibfried, and D. J. Wineland

Recent Bell test experiments that have demonstrated violation of Bell inequalities, have successfully falsified theories of local realism [1-3]. A chained Bell inequality experiment [4], a generalization of the standard Clauser-Horne-Shimony-Holt experiment, utilizes 2N different pairs of measurement settings. The correlations observed in such an experiment can be modeled as a mixture of a local-realistic distribution and a “non-local” distribution that maximally violates the inequality. Using a chained Bell inequality, one can set an upper limit on the fraction of the mixture that satisfies local realism [5-7]. Here, we describe a chained Bell inequality experiment on trapped ions. An entangled pair of trapped Be+ ions is generated using a Mølmer-Sørensen gate [8]. The individual measurement settings are randomized and applied to the ions via single qubit operations. The ions are measured individually with high efficiency. We quantify the local-realistic fraction to be below 0.327 at the 95% confidence level without the fair-sampling or independent-and-identical-distributions assumptions. This work was supported by IARPA, ONR, and the NIST Quantum Information Program. [1] B. Hensen et al., Nature 526, 682 (2015). [2] L. K. Shalm et al, Phys. Rev. Let. 115 250402 (2015). [3] M. Giustina et al., Phys. Rev. Let. 115 250401 (2015). [4] P. M. Pearle, Phys. Rev. D 2, 1418 (1970). [5] A. C. Elitzur, S. Popescu, and D. Rohrlich, Phys. Lett. A 162, 25 (1992). [6] J. Barrett, A. Kent, and S. Pironio, Phys. Rev.Lett. 97, 170409 (2006). [7] P. Bierhorst, J. Phys. A: Math. Theor. 49 215301 (2016). [8] J. P. Gaebler et al., Phys. Rev. Lett. 117, 060505 (2016).

(Session 7 : Friday from 11:30am - 12:00pm)