Superposition, Entanglement, and Limits of Local Causality

Valter Moretti

Jacob A. Barandes

It is difficult to extract reliable criteria for causal locality from the limited ingredients found in textbook quantum theory. In the end, Bell humbly warned that his eponymous theorem was based on criteria that "should be viewed with the utmost suspicion." Remarkably, by stepping outside the wave-function paradigm, one can reformulate quantum theory in terms of old-fashioned configuration spaces together with 'unistochastic' laws. These unistochastic laws take the form of directed conditional probabilities, which turn out to provide a hospitable foundation for encoding microphysical causal relationships. This unistochastic reformulation provides quantum theory with a simpler and more transparent axiomatic foundation, plausibly resolves the measurement problem, and deflates various exotic claims about superposition, interference, and entanglement. Making use of this reformulation, this paper introduces a new principle of causal locality that is intended to improve on Bell's criteria, and shows directly that systems that remain at spacelike separation cannot exert causal influences on each other, according to that new principle. These results therefore lead to a general hidden-variables interpretation of quantum theory that is arguably compatible with causal locality.

Gábor Hofer‐Szabó, Péter Vecsernyés

Tailan S. Sarubi

The distinction between cause and effect represents a significant 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 investigates 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 these violations is essential from a physical standpoint, being a determining factor for understanding quantum causality. Using theoretical models, we identify the critical detection efficiency parameters for different measurement configurations. Additionally, we apply instrumental variables to generate causal inequalities and determine the minimum efficiencies necessary for the violation of these inequalities

Jürgen Audretsch

Osama M. Raisuddin, Suvranu De