Limitations imposed by complementarity

TL;DR

This paper explores how the principle of complementarity in quantum physics limits measurement outcomes, showing that violations lead to non-quantum correlations and potential improvements in quantum state discrimination and cloning.

Contribution

It demonstrates that violating complementarity allows for non-signalling boxes beyond Tsirelson's bound and suggests applications in quantum state discrimination and cloning protocols.

Findings

Violations of complementarity enable non-signalling boxes beyond Tsirelson's bound.

Beyond-quantum objects can improve quantum state discrimination.

Potential for enhanced cloning protocols using these principles.

Abstract

Complementarity is one of the main features of quantum physics that radically departs from classical notions. Here we consider the limitations that this principle imposes due to the unpredictability of measurement outcomes of incompatible observables. For two-level systems, it is shown that any preparation violating complementarity enables the preparation of a non-signalling box violating Tsirelson's bound. Moreover, these "beyond-quantum" objects could be used to distinguish a plethora of non-orthogonal quantum states and hence enable improved cloning protocols. For higher-dimensional systems the main ideas are sketched.