Visualising multiqubit correlatons using the Wigner function

TL;DR

This paper demonstrates how visualizing the Wigner function of multi-qubit states offers detailed insights into their quantum properties, including coherence and entanglement, especially in photonic systems.

Contribution

It introduces a method to visualize and analyze multiqubit correlations using the Wigner function, enhancing understanding beyond traditional density matrix reconstruction.

Findings

Wigner function visualization reveals complex quantum correlations.

Application to photonic systems demonstrates practical utility.

Provides quantitative insights into multi-qubit coherence.

Abstract

Quantum engineering now allows to design and construct multi-qubit states in a range of physical systems. These states are typically quite complex in nature, with disparate, but relevant properties that include both single and multi-qubit coherences and even entanglement. All these properties can be assessed by reconstructing the density matrix of those states - but the large parameter space can mean physical insight of the nature of those states and their coherence can be hard to achieve. Here we explore how the Wigner function of a multipartite system and its visualization provides rich information on the nature of the state, not only at illustrative level but also at the quantitative level. We test our tools in a photonic architecture making use of the multiple degrees of freedom of two photons.