Device-Independent Witness for Entanglement Depth and the Regularization of Finite Statistics for Device-Independent Characterization
May 14th, 2018 PEI-SHENG LIN National Cheng Kung University

In this talk, I will present some Bell-inequalities, involving two dichotomic observables per party, suited for the detection of the genuine many-body entanglement present in quantum states such as the Greenberger-Horne-Zeilinger (GHZ) state and ring-graph state. The inequalities tailored for GHZ states are those presented in [Phys. Rev. Lett. 114, 190401 (2015)] with an additional parameter to improve their abilities to detect also the genuine multipartite entanglement for other states. On the other hand, inequalities for the graph states are obtained from stabilizers of the graph state allowing one to show GHZ paradox. We present a systematic method for finding this kind of inequalities for ring-graph states. Our numerical results suggest that the genuine multipartite entanglement of these as well as some other states can also be witnessed in a device-independent manner. Even though these witnesses work well in the asymptotic scenario, evaluation of their Bell violations using real experimental data is a very subtle task. Indeed, due to finite statistics, it is very likely that the obtained data violates the nosignaling conditions, which contradicts one of the basic premises assumed for device-independent analysis. I will present some of our attempts to overcome this problem.

Seminar, May 14, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Antonio Acín