Researchers at the University of Innsbruck have successfully built a quantum repeater node for standard telecommunication network wavelengths, enabling the transmission of quantum information over tens of kilometres. The team, led by Ben Lanyon, demonstrated the transfer of quantum information over a 50-kilometre-long optical fibre using a quantum repeater placed halfway between the starting and endpoints.
This development could pave the way for a worldwide quantum information network, allowing tap-proof communication and high-performance distributed sensor networks. The Austrian Science Fund FWF, the Austrian Academy of Sciences, and the European Union funded the research.
Quantum Repeater Node for Telecommunication Networks
A new generation of researchers at the University of Innsbruck has successfully built a quantum repeater node for the standard wavelength of telecommunication networks. This achievement comes 25 years after theoretical physicists at the same university first proposed transmitting quantum information via quantum repeaters over long distances, enabling the construction of a worldwide quantum information network.
Quantum networks connect quantum processors or sensors, allowing tap-proof communication and high-performance distributed sensor networks. Quantum information is exchanged between network nodes by photons travelling through optical waveguides. However, the likelihood of photons being lost over long distances increases dramatically.
Quantum Repeater: Light-Matter Entanglement Sources and Memories
To address the issue of photon loss, 25 years ago, Hans Briegel, Wolfgang Dür, Ignacio Cirac, and Peter Zoller provided the blueprints for a quantum repeater. These repeaters feature light-matter entanglement sources and memories to create entanglement in independent network links. The links are then connected by an entanglement swap, which distributes entanglement over long distances.
Building the Core Parts of a Quantum Repeater
Quantum physicists led by Ben Lanyon from the Department of Experimental Physics at the University of Innsbruck have now succeeded in building the core parts of a quantum repeater. This fully functioning network node is made with two single matter systems, enabling entanglement creation with a photon at the standard frequency of the telecommunications network and entanglement swapping operations.
Quantum Repeater Node: Calcium Ions and Optical Resonator
The repeater node consists of two calcium ions captured in an ion trap within an optical resonator and a single photon conversion to the telecom wavelength. The scientists demonstrated quantum information transfer over a 50-kilometre-long optical fibre, with the quantum repeater placed precisely halfway between the starting and endpoints.
Potential for Transmission Over 800 Kilometers
The researchers also calculated which improvements to this design would be necessary to make transmission over 800 kilometres possible. This would allow for the connection of Innsbruck to Vienna. The current results were published in Physical Review Letters, and the research was funded by a START award from the Austrian Science Fund FWF, the Austrian Academy of Sciences, and the European Union, among others. Lanyon’s team is part of the Quantum Internet Alliance, an international project under the EU Quantum Flagship.
“Quantum networks connect quantum processors or quantum sensors with each other. This allows tap-proof communication and high-performance distributed sensor networks,”
Ben Lanyon from the Department of Experimental Physics at the University of Innsbruck.
- Researchers at the University of Innsbruck have built a quantum repeater node for the standard wavelength of telecommunication networks, enabling the transmission of quantum information over tens of kilometres.
- Quantum networks connect quantum processors or sensors, allowing for secure communication and high-performance distributed sensor networks.
- The quantum repeater node was proposed 25 years ago by Hans Briegel, Wolfgang Dür, Ignacio Cirac, and Peter Zoller from the University of Innsbruck.
- The current team, led by Ben Lanyon, successfully built the core parts of a quantum repeater, demonstrating the transfer of quantum information over a 50-kilometre-long optical fibre.
- The researchers also calculated the necessary improvements to enable transmission over 800 kilometres, connecting Innsbruck to Vienna.
- The project is part of the Quantum Internet Alliance, an international initiative under the EU Quantum Flagship. The Austrian Science Fund FWF, the Austrian Academy of Sciences, and the European Union fund it.
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