Counterfactuality, Definiteness, and Bell's Theorem

We show counterfactual definiteness separates classical from quantum physics, by analysing Bell's Theorem. By comparing what it prohibited by various interpretations, we show most interpretations just require counterfactual semi-definiteness (the definiteness of possible options available after a measurement event), rather than full counterfactual indefiniteness. While less definite than classical counterfactual definiteness, it allows us a far more sophisticated tool to consider the physical interpretation of multi-valued variables in a not yet done. Working from this, we further consider its relation to how counterfactual possibilities interact.Comment: 5+1 pages, edited for clarity and concisenes

Comment on "Experimentally adjudicating between different causal accounts of Bell-inequality violations via statistical model selection"

In a recent paper (Phys. Rev. A 105, 042220 (2022)), Daley et al claim that superdeterministic models are disfavoured against standard quantum mechanics, because such models overfit the statistics of a Bell-type experiment which the authors conducted. We argue here that their claim is based on a misunderstanding of what superdeterministic models are.Comment: 4 pages, no figure

Comment on ``Scheme of the arrangement for attack on the protocol BB84"

In a recent paper (Scheme of the arrangement for attack on the protocol BB84, Optik 127(18):7083-7087, Sept 2016), a protocol was proposed for using weak measurement to attack BB84. This claimed the four basis states typically used could be perfectly discriminated, and so an interceptor could obtain all information carried. We show this attack fails when considered using standard quantum mechanics, as expected - such ``single-shot" quantum state discrimination is impossible, even using weak measurement.Comment: 3 pages, 1 figure, accepted for publication by Opti

Comment on "Why interference phenomena do not capture the essence of quantum theory" by Catani et al

It was recently argued by Catani et al that it is possible to reproduce the phenomenology of the double-slit experiment with a deterministic, local, and classical model (arXiv:2111.13727). The stated aim of their argument is to falsify the claim made by Feynman (in his third book of Lectures on Physics) that the double-slit experiment is "impossible, absolutely impossible, to explain in any classical way" and that it "contains the only mystery" of quantum mechanics. We here want to point out some problems with their argument, and defend Feynman's position.Comment: 3 pages, no figures, comments welcom