A Sideways Look at Faithfulness for Quantum Correlations

Despite attempts to apply the lessons of causal modelling observed correlations typical entangled bipartite quantum systems, Wood and Spekkens argue that any model purporting explain these must be fine tuned; is, it violate assumption faithfulness. The faithfulness is a principle parsimony, intuition behind basic compelling: when no statistical correlation exists between occurrences pair events, we have reason for supposing there connection them. This paper an attempt undermine reasonableness in context. Employing symmetry relation system `sideways' consisting single photon passing sequentially through two polarisers, I Spekkens' analysis applies equally this sideways system. If correct, then consequence endorsed by ordinary amounts rejection explanation sideways, system, too. Unless rejecting can sufficiently justified, looks as though tuned, so violation may more tolerable than first thought. Thus extending classical `no fine-tuning' parsimony realm well too hasty.