Contextuality of quantum non-demolition measurement via state discrimination

TL;DR

This paper demonstrates the inherent contextuality in quantum non-demolition measurements, revealing nonclassical features in state discrimination and related quantum processes, with implications for quantum technology.

Contribution

It identifies and analyzes the contextual features of quantum non-demolition measurements, extending to noisy scenarios and practical quantum applications.

Findings

Contextual features distinguish quantum from classical models.

Nonclassicality is demonstrated in unambiguous state discrimination.

Results extend to sequential discrimination and quantum cloning.

Abstract

Quantum non-demolition measurements facilitate various quantum technologies, including quantum communication. Notably, their operational structure can be replicated by a classical model--referred to as a noncontextual model--making it crucial to identify which features prevents such models from reproducing the corresponding quantum measurements. In this work, we theoretically demonstrate contextual features inherent in the structure of quantum non-demolition measurements. These features not only reveal the nonclassicality of unambiguous state discrimination, but also extend to sequential unambiguous discrimination and probabilistic quantum cloning, both of which involve post-measurement states. Moreover, our analysis extends to noisy scenarios, highlighting its potential relevance for practical implementations. We believe that our results broaden the scope of observing nonclassicality in quantum systems and ultimately contribute to the advancement of various quantum technologies.