A Versatile Entanglement-Based Quantum Communication Network

Abstract

Entanglement generation and distribution lie at the heart of quantum information science and technology. In particular, the observation of nonlocal correlations between quantum particles is an essential part of implementing quantum networks. The practical realization of such networks requires the use of fiber-based entangled photon-pair sources with a large bandwidth for easy integration with existing fiber networks as well as increased connectivity using the mature technology of wavelength-division-multiplexing (WDM). Here, we present an entanglement distribution scheme for quantum networks that utilizes a commercially available broadband entangled photon source and WDM technology. The design incorporates an efficient time-multiplexing technique to analyze the polarization correlations and calculate the visibility. In the context of the BBM92 protocol, we explore the trade-off between critical parameters such as the coincidence window, visibility, number of multiplexed wavelength channels, and the key rate. In addition, we discuss different network topologies and their advantages and disadvantages. In a tree-type network configuration, secret key rates between 2.1 and 3.2 bits/s were achievable among four users, with the prospect of scaling up. This study provides valuable insights into the design and implementation of practical and scalable quantum networks.