Sustained state-independent quantum contextual correlations from a single ion

TL;DR

This paper demonstrates a robust, state-independent violation of a non-contextuality inequality using a single trapped-ion qutrit, with a large number of measurements and real-time random measurement selection, confirming fundamental quantum properties.

Contribution

It introduces a novel experimental approach with a single ion to achieve sustained, state-independent quantum contextual correlations through extensive measurement sequences and real-time randomization.

Findings

Violation of non-contextual bound by 214 standard deviations

Sequence of 54 million measurements demonstrating quantumness

Real-time random measurement selection with low latency

Abstract

We use a single trapped-ion qutrit to demonstrate the violation of an input-state-independent non-contextuality inequality using a sequence of randomly chosen quantum non-demolition projective measurements. We concatenate 54 million sequential measurements of 13 observables, and violate an optimal non-contextual bound by 214 standard deviations. We use the same dataset to characterize imperfections including signaling and repeatability of the measurements. The experimental sequence was generated in real time with a quantum random number generator integrated into our control system to select the subsequent observable with a latency below 50 {\mu}s, which can be used to constrain hidden-variable models that might describe our results. The state-recycling experimental procedure is resilient to noise, self-correcting and independent of the qutrit state, substantiating the fact that quantumness is connected to measurements as opposed to designated states.