Joint Unitarity and a Single Definite Outcome in a Quantum Measurement

TL;DR

This paper explores whether a single quantum measurement with a definite outcome can be modeled as a joint unitary evolution, and derives bounds on environment dependence that could test this hypothesis experimentally.

Contribution

It provides a theoretical framework linking measurement outcomes to unitary evolution and proposes an experimental test to challenge or support the orthodox quantum measurement model.

Findings

Derived a lower bound on environment dependence after measurement.

Proposed an experimental test to distinguish between unitary measurement and orthodox collapse.

Linked measurement outcomes to specific unitary evolutions.

Abstract

We investigated the possibility that a single measurement run with a definite outcome is a joint unitary evolution of all the participating systems, and measurement runs with different definite outcomes correspond to different unitary maps. With reasonable assumptions, we derived a lower bound of the dependence of the environment after measurement on the state of the system before measurement, conditioned on the same measurement outcome. An experimental test of this dependence relation can either serve as evidence that the unitary dynamics and the definite outcome in the orthodox sense cannot be true together or suggest a deviation from the von Neumann measurement model plus a "conditioning" interpretational step.