Three-Color Entanglement

TLDR

Entanglement is a key quantum resource for speeding up information processing and enabling advanced quantum communication, and quantum networks will rely on entangled light beams, prompting exploration of diverse physical systems and hybrid architectures. The authors introduce a tool that connects systems lacking common resonance frequencies by directly generating entanglement among three bright light beams of distinct wavelengths (532.251 nm, 1062.102 nm, and 1066.915 nm). They achieve the first direct generation of entanglement among three bright beams of different wavelengths and observe, for the first time, disentanglement under finite channel losses, the continuous‑variable analogue of entanglement sudden death.

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.