Entropic Dynamics approach to Relational Quantum Mechanics

TL;DR

This paper develops a non-relativistic relational quantum mechanics framework using Entropic Dynamics, emphasizing information-theoretic principles and addressing the problem of time in quantum gravity.

Contribution

It introduces a novel entropic dynamics approach to relational quantum mechanics, incorporating information geometry and symplectic structures, and proposes quantum constraints on expectation values.

Findings

Models are partially relational, retaining absolute simultaneity and Euclidean geometry.

ED provides a new measure of state mismatch based on information metrics.

The approach offers a way to avoid the problem of time in quantum gravity.

Abstract

The general framework of Entropic Dynamics (ED) is used to construct non-relativistic models of relational quantum mechanics from well known inference principles -- probability, entropy and information geometry. Although only partially relational -- the absolute structures of simultaneity and Euclidean geometry are still retained -- these models provide a useful testing ground for ideas that will prove useful in the context of more realistic relativistic theories. The fact that in ED the positions of particles have definite values, just as in classical mechanics, has allowed us to adapt to the quantum case some intuitions from Barbour and Bertotti's classical framework. Here, however, we propose a new measure of the mismatch between successive states that is adapted to the information metric and the symplectic structures of the quantum phase space. We make explicit that ED is temporally relational and we construct non-relativistic quantum models that are spatially relational with respect to rigid translations and rotations. The ED approach settles the longstanding question of what form should the constraints of a classical theory take after quantization: the quantum constraints that express relationality are to be imposed on expectation values. To highlight the potential impact of these developments, the non-relativistic quantum model is parametrized into a generally covariant form and we show that the ED approach evades the analogue of what in quantum gravity has been called the problem of time.