Test of transient deviations from Quantum Mechanics in Bell's experiment (2404.09759v1)

Abstract: The conflict between Quantum Mechanics (QM) and Local Realism is most noticeable in the correlations observed between distant regions of a spatially spread entangled state. It has been hypothesized that transient deviations (from the values predicted by QM) may be observed if the correlations are measured in a time shorter than L/c, where L is the spatial spread of the entangled state and c is the speed of light. This hypothesis is appealing for it solves that conflict by minimally modifying the interpretation of QM, and opens the door to potentially fruitful nonlinear generalizations of QM without the risk of allowing faster-than-light signaling. The hypothesis is technically impossible to test directly nowadays, but a stroboscopic test is attainable. We present the results of such a test performed on a specially designed optical Bell setup with a distance between stations up to 24 m in straight line. No difference with the same observations performed at short distance, or evidence of transient deviations, is found. Yet, several hypotheses are involved in this experiment; they are detailed and briefly discussed. To say the least, the space left for the hypothesis of transient deviations is much reduced.