What is the future of quantum information

05.11.2020 11:37

Physicists develop efficient modems for future quantum internet

Max Planck Institute for Quantum Optics Press and public relations
Max Planck Institute for Quantum Optics

Physicists at the Max Planck Institute for Quantum Optics have developed the basic technology for a new “quantum modem” with which quantum information can be sent through the existing fiber optic network in the future. The realization of a quantum Internet is thus a step closer.

The first quantum revolution brought about semiconductor electronics, the laser, and finally the internet. The second quantum revolution promises tap-proof communication or quantum computers for previously unsolvable computing tasks. But this revolution is still in the baby socks. A central research object is the interface between local quantum devices and the remote transmission of highly sensitive quantum information through light quanta. The Otto Hahn group “Quantum Networks” at the Max Planck Institute for Quantum Optics in Garching, headed by Andreas Reiserer, is researching such a “quantum modem”. The team has now achieved a first breakthrough to a relatively simple but highly efficient technology that can be integrated into existing fiber optic networks. The work appears today in the journal "Physical Review X".

Global quantum network as a goal

The quantum internet is about the global networking of new technologies that use quantum physics consistently like never before. However, this requires suitable interfaces for the extremely sensitive quantum information, which is an enormous technical challenge. Therefore, such interfaces are a central construction site for basic research. You have to ensure that quiescent quantum bits - qubits for short - interact efficiently with "flying" qubits for remote communication without destroying the quantum information, with as little loss as possible. Quiet qubits are located in the local devices, for example as a memory or processor of a quantum computer.
Flying qubits are usually light quanta, photons that transport quantum information through the air, the vacuum of space or through fiber optic networks.

The "quantum modem" should efficiently establish a connection between flying and resting qubits. For this purpose, the team around Andreas Reiserer and doctoral student Benjamin Merkel has developed a new technology and has just demonstrated its basic functionality. Your decisive advantage: It could be integrated into the existing telecommunications fiber optic network. This would be the fastest way to promote functioning remote networking of quantum technologies.

Tailor-made quantum leap

The new technology uses erbium atoms as resting qubits. Because in them an electron can make a quantum leap that directly matches the standard infrared wavelength of the photons in the fiber optic networks. However, the photons have to shake the erbium atoms intensely for the quantum leap to occur. To do this, the team packed the atoms in a transparent crystal made from a yttrium silicate compound that is five times thinner than a human hair. This crystal in turn comes like a sandwich spread between two almost perfect mirrors. In the mirror cabinet, the photons fly back and forth like ping-pong balls. Each time they cross the crystal. In this way, they encourage the erbium atoms to make their quantum leap much more efficiently and almost sixty times faster than without this mirror cabinet. Since the mirrors, despite their perfection, are also somewhat permeable to the photons, the modem can connect to the network.

The team was now able to demonstrate that this principle works very successfully and efficiently. The Garching quantum modem is still purely basic research. But it has the potential to advance the technical realization of a quantum Internet.

This is a short version. You can read a more detailed version here: https://www.mpq.mpg.de/modem-quanteninternet

Scientific contact:

Dr. Andreas Reiserer
Research group leader
Max Planck Institute for Quantum Optics
Hans-Kopfermann-Str. 1
85748 Garching, Germany
Tel: +49 89 3 29 05 - 759 // -222
Email: [email protected]

Original publication:

Benjamin Merkel, Alexander Ulanowski, and Andreas Reiserer, Coherent and Purcell-Enhanced Emission from Erbium Dopants in a Cryogenic High-Q Resonator, Phys. Rev. X 10, 041025, https://doi.org/10.1103/PhysRevX.10.041025

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Features of this press release:
Physics / astronomy
research results