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Aephraim Steinberg
University of Toronto, CA

Experimental studies of quantum reality

I will present a number of experiments underway at Toronto using weak measurements and Bohmian mechanics to investigate what can be said about the ontology of quantum systems, specifically ones constrained by boundary conditions at both early and late times. I will begin by reviewing an experiment in which “the result of counting a single photon can be a value of 8,” and address questions about whether or not one should think of such anomalous results of weak measurements as reflecting something about reality. I will show that a realistic ontology such as Jaynes’s “neoclassical electromagnetism” would in fact lead to predictions in excellent agreement with our observations – but also that there is an experimentally accessible regime where this would break down. This is a follow-up experiment we plan to pursue in the future. I will also describe several other ongoing experiments: one which studies the essential differences between Bohm-like models which treat either position or momentum as the possible ontological variables; one in which we propose to expose the different histories experienced by particles which traverse a tunnel barrier and those which are reflected; and one where the quantum pigeonhole paradox will be used as an arena for exploring various bounds and sum rules one might expect to hold, some of which turn out to hold for strong but not for weak measurements, while others hold for weak but not for strong measurements. We believe that these experiments contribute to an evolving understanding of the elements of reality which one can ascribe to post-selected quantum systems, and to how one should attempt to view the reality underlying quantum theory more broadly.
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