Room Temperature Quantum Repeater Advance

Created November 29, 2018
Researchers Michael Zugenmaier and Karsten Dideriksen next to their experimental setupApplications and Research

Researchers at the Niels Bohr Institute, University of Copenhagen, have recently succeeded in boosting the storage time of quantum information. The development used a small glass container filled with room temperature atoms, and marked an important step towards a secure quantum encoded distribution network and the realisation of real-world quantum repeaters.

The researchers note that storage time comes into the quantum communications equation, as it actually takes some time for the information to travel in fibres. The delicate quantum entanglement has to be stored, waiting its turn to travel through the optical fibre. Accordingly, it makes very good sense to aim for a system that operates at room temperature, because of the scale of such networks. If quantum repeaters have to be deployed for approximately every 10 km of communication line, the benefits of a simple setup, working at room temperature, are tremendous.

The researchers at the Niels Bohr Institute have managed to boost this crucial lifespan of the quantum state at room temperature to about a quarter of a millisecond. In this period of time the light can travel roughly 50 km in the fibre. “So, 50 km – it is still not very far, if you want to send regional quantum information, but it is way longer than what has previously been achieved with atoms at room temperature”, reported Karsten Dideriksen, PhD student on the project.

The Niels Bohr Institute technique itself consists of a small glass container, filled with Cæsium atoms, in which the researchers are able to load, store and retrieve single photons from the quantum states necessary for the repeater. This technique improves the life span of the quantum states at room temperature by a hundred times. Simplicity is key, as one has to imagine this technology, once developed to its full potential, spread out across the globe as quantum repeaters in our information networks.

The immediate use-case is storage for secure quantum information networks, but other options such as generation of on-demand single photons for quantum computing are on the table.

The researchers involved in this study were: postdoc Michael Zugenmaier; PhD student Karsten B. Dideriksen; Prof. Anders S. Sørensen; PhD Boris Albrecht; and Prof. Eugene S. Polzik. The research was published in Nature Communications.

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This article was written
by John Williamson

John Williamson is a freelance telecommunications, IT and military communications journalist. He has also written for national and international media, and been a telecoms advisor to the World Bank.