Experimental investigation of dynamical invariants in bipartite entanglement

TL;DR

This paper experimentally demonstrates that adding a third party to a bipartite entangled system can lead to a conservation law for entanglement, revealing new dynamical invariants in multipartite quantum systems.

Contribution

It introduces a novel conservation law for bipartite entanglement in the presence of a third party and experimentally verifies this in photon-based systems.

Findings

Conservation law relates bipartite entanglement quantities with a third party.

Experimental validation using entangled photon systems.

Generalization to N-partite GHZ states.

Abstract

The non-conservation of entanglement, when two or more particles interact, sets it apart from other dynamical quantities like energy and momentum. It does not allow the interpretation of the subtle dynamics of entanglement as a flow of this quantity between the constituents of the system. Here we show that adding a third party to a two-particle system may lead to a conservation law that relates the quantities characterizing the bipartite entanglement between each of the parties and the other two. We provide an experimental demonstration of this idea using entangled photons, and generalize it to N-partite GHZ states.