Entanglement combing

TL;DR

This paper demonstrates that any multi-partite pure quantum state can be transformed into a set of pairwise entangled states with a specific party, preserving entanglement and enabling new quantum information applications.

Contribution

It introduces a protocol for lossless entanglement distribution among parties, classifies possible entanglement configurations, and highlights applications in quantum information processing.

Findings

All multi-partite pure states can be transformed into pairwise entangled states.

The entanglement of a distinguished party with others remains unchanged after transformation.

The set of achievable entanglement distributions is classified.

Abstract

We show that all multi-partite pure states can, under local operations, be transformed into bi-partite pairwise entangled states in a "lossless fashion": An arbitrary distinguished party will keep pairwise entanglement with all other parties after the asymptotic protocol - decorrelating all other parties from each other - in a way that the degree of entanglement of this party with respect to the rest will remain entirely unchanged. The set of possible entanglement distributions of bi-partite pairs is also classified. Finally, we point out several applications of this protocol as a useful primitive in quantum information theory.