1202.0141 (Tobias Fritz)

Polyhedral duality in Bell scenarios with two binary observables    [PDF]

Tobias Fritz

For the Bell scenario with two parties and two binary observables per party,
it is known that the no-signaling polytope is the polyhedral dual (polar) of
the Bell polytope. Computational evidence suggests that this duality also holds
for three parties. Using ideas of Werner, Wolf, \.Zukowski and Brukner, we
prove this for any number of parties by describing a simple linear bijection
mapping (tight) Bell inequalities to (extremal) no-signaling boxes and vice
versa. Furthermore, a symmetry-based technique for extending Bell inequalities
(resp. no-signaling boxes) with two binary observables from n parties to n+1
parties is described; the Mermin-Klyshko family of Bell inequalities arises in
this way, as well as 11 of the 46 classes of tight Bell inequalities for 3
parties. Finally, we ask whether the set of quantum correlations is self-dual
with respect to our transformation. We find this not to be the case in general,
although it holds for 2 parties on the level of correlations. This self-duality
implies Tsirelson's bound for the CHSH inequality.

View original: http://arxiv.org/abs/1202.0141