1301.1448 (I-Ching Yu et al.)

Testing Information Causality for General Quantum Communication
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I-Ching Yu, Feng-Li Lin

Information causality has been proposed to constrain the maximal mutual information shared between sender and receiver in a communication protocol based on physical theories such as quantum mechanics. In this paper, we test this proposal for the more general quantum communication protocols with multi-level and (non-)symmetric channels by directly evaluating the mutual information. We utilize the random-access code and no-signaling boxes to formulate the Bell-type inequalities and semidefinite programming to find the generalized Tsireslon bound. Our results support the information causality which is never violated for the more general settings discussed in this work. For the 2-level and 2-setting cases, we also find that the information causality is saturated not for the channels with the maximal quantum non-locality associated with the Tsirelson's inequality but for the marginal cases saturating the Bell's inequality. This indicates that the more quantum non-locality may not always yield the more mutual information.

View original: http://arxiv.org/abs/1301.1448