Detection efficiency in quantum violations of causal bounds
Non-locality, Causal bounds, Detection efficiency.
The distinction between cause and effect is a major challenge in physics, especially when dealing with correlated events. In quantum mechanics, this complexity is further accentuated due to phenomena such as superposition and quantum entanglement, which result in "instantaneous" correlations between distant systems, known as quantum non-locality. This work addresses the detection efficiency in quantum violations of causal limits, which are inequalities that must be respected by any local classical theory. Determining the minimum conditions necessary for detection efficiency to allow the observation of such a violation is crucial from a physical standpoint, as it is a determining factor for understanding how quantum causality works. Using theoretical models, we identify the critical detection efficiency parameters for different measurement configurations, employ instrumental variables to generate do-inequalities, and find the minimum efficiencies necessary for the violation of these inequalities.