Zenith Grant Awardee

Miguel Navascués

Bilkent University

Project Title

Towards an almost quantum physical theory

Project Summary

Conceived circa 1932, Quantum Mechanics has so far not failed in providing an accurate picture of the world. Some of its predictions, such as the anomalous magnetic moment of the electron, have been verified experimentally up to a precision of 10 decimal digits. In addition, quantum mechanics is the basis for most of the technology around us, like computers, lasers and mobile phones. At the same, time, quantum mechanics is full of conceptual problems; its description of physical systems as simple as a copper bar is complicated to the point of becoming useless; and cannot be reconciled with gravity in a straightforward way. And yet we physicists keep clinging to it. Why? Mainly because we don’t have an alternative theory. Previous attempts to extend or generalize quantum mechanics have led to scientific theories with extremely unphysical features, such as faster-than-light communication. In an earlier work, we studied physical theories from the point of view of the correlations that they generate between different events. Our research suggests that there could exist a physical theory beyond quantum and also points where to find it. The goal of the project is to identify such a theory and test it experimentally against quantum mechanics.

Technical Abstract

In the last years, there have been several attempts to understand quantum nonlocality via physical principles alone, i.e., without any reference to the mathematical structure behind quantum theory. Essentially, there have been five proposals: Non-trivial Communication Complexity, No Advantage for Nonlocal Computation, Information Causality, Macroscopic Locality and Local Orthogonality. Recently, we identified a supra-quantum set of correlations that does not violate any of the aforementioned principles. We call it the almost quantum set. It emerges naturally in a consistent histories approach to theories beyond quantum mechanics, and, contrary to the quantum set, whose characterization we do not even know to be decidable, it admits a computationally efficient description. We conjecture that the almost quantum set corresponds to the set of correlations of a yet-to-be-discovered consistent physical theory; similar to quantum mechanics, albeit arguably more plausible. The main goal of this project is to search for such a theory, i.e., to formulate a complete physical theory whose nonlocal correlations are described by the almost quantum set, and to identify concrete experimental scenarios where the predictions of quantum and almost quantum mechanics differ. Ultimately, we ambition to disprove quantum theory via a Bell-type experiment.