External quantum fluctuations select measurement contexts

TL;DR

This paper investigates how external quantum fluctuations influence the selection of measurement contexts in quantum mechanics, revealing that different outcomes can correspond to different contexts even within a single measurement setup.

Contribution

It demonstrates that initial states of measurement apparatuses, representing quantum fluctuations, are crucial in selecting measurement contexts, especially beyond idealized measurements.

Findings

External quantum fluctuations determine measurement context selection.

Different outcomes in a single setup can represent different contexts.

Contextuality can occur without measurement incompatibility.

Abstract

Quantum paradoxes show that the outcomes of different quantum measurements cannot be described by a single measurement-independent reality. Any theoretical description of a quantum measurement implies the selection of a specific measurement context. Here, we investigate generalised quantum measurements, in order to identify the mechanism by which this specific context is selected. We show that external quantum fluctuations, represented by the initial state of the measurement apparatus, play an essential role in the selection of the context. This has the non-trivial consequence that, when considering measurements other than just idealised projection-valued measures, different outcomes of a single measurement setup can represent different measurement contexts. We further show this result underpins recent claims that contextuality can occur in scenarios without measurement incompatibility.