Generalised ontological models based on processes

TL;DR

This paper introduces a novel class of ontological models for quantum theory where states are represented as processes rather than static ontic states, challenging traditional classifications of quantum states as ontic or epistemic.

Contribution

It proposes a generalized ontological framework based on processes, extending beyond standard models, and connects to the PBR model in specific cases.

Findings

Quantum states are modeled as ongoing processes, not static states.

Measurement outcomes depend on the entire process path, not just the ontic state.

The model bridges to standard ontological models like PBR in special cases.

Abstract

In this paper, we explore realist models of quantum theory that does not fit into the standard definitions of ontological models. The models here go beyond standard definition of ontological models in the sense that quantum states do not correspond to distributions over the ontic state space and a system prepared in a quantum state is not in an ontic state. Instead, a system in a quantum state is always in a process, i.e. moving around in the ontic state space. Also, quantum measurement outcomes are not direct measurement of the ontic state, but depend probabilistically on the entire path the system takes during the measurement process. Consequently, we explain how, in our model, quantum states can neither be classified as ontic nor epistemic in the sense of knowledge about an underlying reality. In our model, quantum probabilities describes our (objective) knowledge about measurement outcomes. We also look at two hybrid models where either the preparation or measurement do follow the definitions in standard ontological models. Lastly, we propose a form of generalised ontological model that reduces to the standard PBR model when the underlying process reduces to a point in ontic space.