Distinct Quantum States Can Be Compatible with a Single State of Reality

TL;DR

This paper explores models where multiple quantum states can correspond to the same underlying reality, suggesting that quantum states may represent information rather than direct physical states, and highlights the need for extra assumptions to exclude such models.

Contribution

It demonstrates through examples that models with overlapping quantum states and a single underlying reality are possible, emphasizing the necessity of additional assumptions to rule them out.

Findings

Multiple quantum states can be compatible with a single underlying physical state.

Additional assumptions are required to exclude models with overlapping quantum states.

The interpretation of the quantum state as information rather than reality is plausible.

Abstract

Perhaps the quantum state represents information about reality, and not reality directly. Wave function collapse is then possibly no more mysterious than a Bayesian update of a probability distribution given new data. We consider models for quantum systems with measurement outcomes determined by an underlying physical state of the system but where several quantum states are consistent with a single underlying state---i.e., probability distributions for distinct quantum states overlap. Significantly, we demonstrate by example that additional assumptions are always necessary to rule out such a model.