Experimental demonstration of three-color entanglement

TL;DR

This paper demonstrates the first direct generation of three-color entangled light beams at different wavelengths, advancing quantum communication by connecting diverse systems and exploring entanglement loss under channel losses.

Contribution

It introduces a novel experimental setup that produces three-color entanglement and investigates entanglement disentanglement due to channel losses.

Findings

First demonstration of three-color entanglement among bright beams.

Observation of disentanglement caused by finite channel losses.

Analysis of entanglement sudden death in continuous variables.

Abstract

Entanglement is the essential quantum resource for a potential speed-up of information processing, as well as for sophisticated quantum communication. Quantum information networks will be required to convey information from one place to another, by using entangled light beams. Many physical systems are under consideration as building blocks, with different merits and faults, so that hybrid systems are likely to be developed. Here we present an important tool for connecting systems that share no common resonance frequencies: we demonstrate the first direct generation of entanglement among more than two bright beams of light, all of different wavelengths (532.251 nm, 1062.102 nm, and 1066.915 nm). We also observe, for the first time, disentanglement for finite channel losses, the continuous variable counterpart to entanglement sudden death.