Entanglement concentration after a multi-interactions channel

TL;DR

This paper presents a theoretical and experimental study of an entanglement concentration protocol that probabilistically recovers entanglement in a three-qubit mixed state after passing through a noisy, multi-interaction channel, including sequential couplings.

Contribution

It introduces a novel entanglement concentration method applicable to mixed states after multiple noisy interactions, demonstrating full entanglement recovery.

Findings

Successful probabilistic entanglement recovery after a single interaction.

Full entanglement recovery is possible even after multiple depolarizing interactions.

Experimental validation confirms theoretical predictions.

Abstract

Different procedures have been developed in order to recover entanglement after propagation over a noisy channel. Besides a certain amount of noise, entanglement is completely lost and the channel is called entanglement breaking. Here we investigate both theoretically and experimentally an entanglement concentration protocol for a mixed three-qubit state outgoing from a strong linear coupling of two-qubit maximally entangled polarization state with another qubit in a completely mixed state. Thanks to such concentration procedure, the initial entanglement can be probabilistically recovered. Furthermore, we analyse the case of sequential linear couplings with many depolarized photons showing that thanks to the concentration a full recovering of entanglement is still possible.