Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fiber-based quantum communication - Interference of photons using remote sources

23.10.2018

Scientists are working on the totally bug-proof communication – the so-called quantum communication. Current approaches for long-distance signal transmission rely on repeaters which are based on a crucial effect, the interference of two photons, that is, two individual light quanta coming from distant sources. Physicists from University of Stuttgart and Saarland University, in Germany, were now able to manipulate the single photons by means of small crystals without compromising their quantum mechanical nature. This manipulation is necessary to transmit the signal via optical fibers which may enable a large-area quantum network. The results were now published in Nature Nanotechnology.

Quantum networking is based on the transmission of single photons being used as “flying” quantum bits. The probability to detect a single photon upon fiber transmission decreases exponentially with increasing fiber distance. It is therefore necessary, to use photons with specific wavelength such that transmission within a range of 10 to 100 km is possible via optical fibers. Nevertheless, the quantum signal has still to be repeated as in classical communication channels.


Emission of single photons stemming from remote quantum dots. The wavelength of the single photons is manipulated by mixing them with strong laser fields within small crystals.

University of Stuttgart/Kolatschek

However, such “quantum repeaters” are fundamentally different to repeaters of classical communication as they have to bridge the intermediate distance by means of quantum mechanical effects. The building block of such a technology is the interference of two photons stemming from remote quantum emitters. “In this experiment, we use semiconductor nanostructures as sources of single photons.

They have the big potential to emit single photons at record rates”, says Jonas Weber. The PhD student at the University of Stuttgart is in charge of the handling of the quantum light sources, therefore of the generation and interference of the single photons. “High emission rates are crucial for high data transfer”, further explains Jonas Weber.

The typically used nanostructures, which are referred to as quantum dots, emit photons in a wavelength range which is not compatible with optical fibers. To still exploit the advantages and perspectives of quantum dots, the Quantum Optics group at Saarland University, led by Prof. Christoph Becher, built two independent quantum frequency converters.

With such devices, the emitted photons are mixed with strong laser beams, such that their wavelength is converted and thus prepared for transmission in optical fibers. “Only because of this manipulation, the photons can be transmitted over 10-100 km fiber distance. Without this procedure, every kilometer the signal would have to be repeated.

This wouldn’t be feasible at all”, says Benjamin Kambs, the PhD student in the group of Prof Becher, who was in charge of building and optimizing the two frequency converters.

The physicists were able to show that the necessary photon manipulation does not compromise the quantum mechanical nature of the light. Based on that premises, the emitted photons were sent through 2 km optical fiber and still successfully brought to interference. This is a non-negligible fact, given the rather fragile nature of such quantum states.

“This complex experiment was only possible because of the long-lasting collaboration between Saarland University and University of Stuttgart. It was successful due to a remarkable team work and it shows that quantum dots in combination with quantum frequency conversion are a viable platform for future quantum repeater scenarios”, says Peter Michler, head of the IHFG, University of Stuttgart.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Peter Michler, Universität Stuttgart, Institut für Halbleiteroptik und Funktionelle Grenzflächen, Tel.:+49 (0)711/685-64660, p.michler@ihfg.uni-stuttgart.de

Originalpublikation:

Publication: J. H. Weber, B. Kambs et al., Two-photon interference in the telecom C-band after frequency conversion of photons from remote quantum emitters, Nature Nanotechnology, 2018; https://doi.org/10.1038/s41565-018-0279-8

Andrea Mayer-Grenu | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-stuttgart.de/

More articles from Information Technology:

nachricht Next generation photonic memory devices are light-written, ultrafast and energy efficient
15.01.2019 | Eindhoven University of Technology

nachricht Overtones can provide faster data communication
10.01.2019 | University of Gothenburg

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

Im Focus: Programming light on a chip

Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...

Im Focus: Physicists uncover new competing state of matter in superconducting material

A team of experimentalists at the U.S. Department of Energy's Ames Laboratory and theoreticians at University of Alabama Birmingham discovered a remarkably long-lived new state of matter in an iron pnictide superconductor, which reveals a laser-induced formation of collective behaviors that compete with superconductivity.

"Superconductivity is a strange state of matter, in which the pairing of electrons makes them move faster," said Jigang Wang, Ames Laboratory physicist and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

 
Latest News

Scientists coax proteins to form synthetic structures with method that mimics nature

15.01.2019 | Life Sciences

Next generation photonic memory devices are light-written, ultrafast and energy efficient

15.01.2019 | Information Technology

Viennese scientists develop promising new type of polymers

15.01.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>