Qcrypt 2022: Poster159
Self-testing quantum correlations on the no-signaling boundary
Authors
Kai-Siang Chen (National Cheng Kung University); Jun-Yi Wu (Tamkang University); Gelo Noel M. Tabia (National Cheng Kung University); Jebarathinam Chellasamy (Center for Theoretical Physics, Polish Academy of Sciences); Yeong-Cherng Liang (National Cheng Kung University); Shiladitya Mal (National Cheng Kung University)
Abstract
In device-independent quantum information, correlations between local measurement outcomes observed by spatially separated parties in a Bell test play a fundamental role. Even though it is long-known that the set of correlations allowed in quantum theory lies strictly between the Bell-local set and the no-signaling set, many questions concerning the geometry of the quantum set remain unanswered. Here, we revisit the problem of when the boundary of the quantum set coincides with the no-signaling set in the simplest Bell scenario. In particular, we prove that self-testing is possible in several classes of these common boundaries beyond the known example of Hardy-type correlations. An analogous characterization for the set M of quantum correlations arising from finite-dimensional maximally entangled states is also provided. En route to establishing this last result, we show that all extreme points of M in the simplest Bell scenario can be attained using a Bell pair and projective measurements. In turn, this enables us to derive the maximal Clauser-Horne-Shimony-Holt Bell inequality violation by any maximally entangled two-qudit state.
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