Study highlights current State of Research, technological Approaches, and possible Development Pathways for Quantum Repeaters:
Quantum Repeaters are considered a key building block for future Quantum Networks. To date, the control, storage, and distribution of Quantum Information and entanglement remain major challenges. Unlike classical telecommunications signals, Quantum Information cannot be copied or amplified arbitrarily due to the laws of Quantum Mechanics. As a result, current approaches to Quantum Communication are limited in terms of range and scalability. Quantum Repeaters could provide a solution in the future: They are intended to distribute Quantum Information and entanglement over long distances, thereby enabling applications such as secure Quantum Communication via Quantum Key Distribution (QKD), distributed Quantum Computing, or Quantum Sensor Networks over extended distances. They are therefore considered an essential prerequisite for powerful Quantum Networks of the future.
Against this background, the Fraunhofer-Institut für System- und Innovationsforschung (ISI), together with Universität des Saarlandes (UdS), has published a new technology roadmap within the framework of the umbrella project for Quantum Communication in Germany (SQuaD). The roadmap analyzes the current state of research, compares different technological approaches, and outlines possible development steps towards future Quantum Repeaters. It is based on a comprehensive analysis of scientific literature as well as assessments from 22 experts from academia and industry, collected through individual interviews and an online roadmapping workshop. The aim of the roadmapping process was to assess the technological maturity level, identify key challenges, and highlight potential development pathways.
The results show that research in this field is developing dynamically worldwide. In recent years, research groups have achieved important advances in key repeater functionalities. At the same time, the technology field is still at an early stage of development. A commercially viable Quantum Repeater capable of distributing entanglement over large distances more efficiently than direct transmission is therefore still expected to be several years away. Various hardware platforms are currently being intensively researched, including color centers in diamond, individual atoms and ions as well as ensembles of these systems, rare-earth ions, and Quantum Dots. So far, none of these platforms has clearly emerged as the leading approach. Instead, the different approaches each offer specific strengths and weaknesses, for example regarding storage times, efficiency, scalability, or integration capabilities. The authors therefore see good reasons to pursue multiple technological pathways in parallel. Hybrid systems that combine different platforms could also become increasingly important in the future.
However, significant scientific and technological challenges still need to be overcome before Quantum Repeaters can be widely deployed. These include, among others, improving efficiency, extending storage times, increasing transmission rates, integrating systems into existing telecommunications infrastructures, as well as standardization and industrial scaling. Nevertheless, researchers expect further demonstrations of individual components and network functionalities in the coming years. Before 2035, first Quantum Repeaters could be demonstrated that transmit entanglement or Quantum Information over long distances with lower losses than direct connections. This would represent a significant milestone on the path towards powerful Quantum Networks.
Source references: https://www.isi.fraunhofer.de/en/presse/2026/presseinfo-12-quanteninformation-ueber-grosse-distanzen.html; https://www.linkedin.com/posts/fraunhoferisi_how-can-quantum-information-be-transmitted-activity-7488505378968604672-vzaL/?utm_source=share&utm_medium=member_desktop&rcm=ACoAADSzuCQBOAdSaUa850kDF-Ysbt1C6WM-_r4