# Noise-robust preparation contextuality shared between any number of observers via unsharp measurements

## TL;DR

This paper demonstrates that multiple independent observers can share quantum preparation contextuality using unsharp measurements, even with noise, revealing the robustness and shareability of quantum correlations.

## Contribution

It introduces a method for sharing preparation contextuality among any number of observers via unsharp measurements, including in noisy conditions.

## Key findings

- Shared preparation contextuality can be demonstrated by multiple observers.
- Unsharp measurements enable sharing of quantum correlations.
- Experimental realization confirms theoretical predictions.

## Abstract

Multiple observers who independently harvest nonclassical correlations from a single physical system share the system's ability to enable quantum correlations. We show that any number of independent observers can share the preparation contextual outcome statistics enabled by state ensembles in quantum theory. Furthermore, we show that even in the presence of any amount of white noise, there exists quantum ensembles that enable such shared preparation contextuality. The findings are experimentally realised by applying sequential unsharp measurements to an optical qubit ensemble which reveals three shared demonstrations of preparation contextuality.