A survey on advances of quantum repeater

¹ College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications - Nanjing 210003, China
² School of Science, Nanjing University of Posts and Telecommunications - Nanjing, 210003, China
³ Institute of Quantum Information and Technology, Nanjing University of Posts and Telecommunications Nanjing 210003, China

^(a) shengyb@njupt.edu.cn (corresponding author)

Received: 12 October 2021
Accepted: 9 November 2021

Abstract

The distribution of quantum entanglement is essential for quantum communication. Contrary to classical communication, the signal in quantum communication is impossible to copy due to the basic principles of quantum mechanics, i.e., quantum state collapse and no-cloning theorem. However, the communication range is limited by inevitable photon loss. To counteract this issue, one can insert several repeater stations between two remote end nodes to divide the full distance into several shorter segments and successively operate entanglement swapping between adjacent repeater stations to enable long-distance quantum communication. Up to now, one can classify quantum repeaters (QRs) into three generations based on the methods of reducing errors resulted from photon loss and imperfect operations. In this paper, we will briefly review advances for each generation of QRs and discuss the advantages and challenges of each generation. Moreover, we also discuss some efficient proposals of building blocks to overcome the bottlenecks for QRs.