Multipartite entanglement of superpositions

TL;DR

This paper generalizes the concept of entanglement in superpositions to multipartite systems, providing tight bounds and extending to various entanglement measures, enhancing understanding of complex quantum states.

Contribution

It introduces a tight upper bound on multipartite entanglement of superpositions and extends the result to multiple entanglement quantifiers.

Findings

Derived a tight upper bound for multipartite entanglement of superpositions.

Extended the bound to measures like negativity and robustness of entanglement.

Applicable to states with an arbitrary number of qubits.

Abstract

The entanglement of superpositions [Phys. Rev. Lett. 97, 100502 (2006)] is generalized to the multipartite scenario: an upper bound to the multipartite entanglement of a superposition is given in terms of the entanglement of the superposed states and the superposition coefficients. This bound is proven to be tight for a class of states composed by an arbitrary number of qubits. We also extend the result to a large family of quantifiers which includes the negativity, the robustness of entanglement, and the best separable approximation measure.