Fibre based hyperentanglement generation for dense wavelength division multiplexing

TL;DR

This paper presents a guided-wave method for generating hyperentangled photons in multiple degrees of freedom at telecom wavelengths, enhancing quantum communication capacity and demonstrating Bell inequality violations.

Contribution

It introduces a fully guided-wave approach for hyperentanglement generation in polarization and energy-time, compatible with fiber networks and significantly increasing quantum channel capacity.

Findings

Successful generation of polarization and energy-time hyperentangled photons at telecom wavelengths.

Demonstration of compliance with fiber network standards through spectral demultiplexing.

Violation of a generalized Bell inequality by more than 27 standard deviations.

Abstract

Entanglement is a key resource in quantum information science and associated emerging technologies. Photonic systems offer a large range of exploitable entanglement degrees of freedom such as frequency, time, polarization, and spatial modes. Hyperentangled photons exploit multiple degrees of freedom simultaneously to enhance the performance of quantum information protocols. Here, we report a fully guided-wave approach for generating polarization and energy-time hyperentangled photons at telecom wavelengths. Moreover, by demultiplexing the broadband emission spectrum of the source into five standard telecom channel pairs, we demonstrate compliance with fibre network standards and improve the effective bit rate capacity of the quantum channel up to one order of magnitude. In all channel pairs, we observe a violation of a generalised Bell inequality by more than 27 standard deviations, underlining the relevance of our approach.