Just posted on the arXive the paper: “Unobservable causal loops explain both the quantum computational speedup and quantum nonlocality”. The link is:
http://arxiv.org/abs/2011.14680
I show that the ordinary quantum description of the reversible process between two one-to-one correlated measurement outcomes is the quantum superposition of unobservable time-symmetrized instances whose causal structure is completely defined.
Such instances have a superior explanatory power of the phenomenon at stake than their quantum superposition. They exactly explain both the quantum computational speedup and quantum nonlocality. In the former case the two measurement outcomes are the setting and the solution of the problem, in the latter the outcomes of measuring in the same basis two maximally entangled observables in a state of space-separation of the respective subsystems.
In the speedup case, the explanation is quantitative in character. Given an oracle problem, it yields the number of oracle queries needed to solve it in an optimal quantum way.