Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Entangling photons from a quantum dot in the telecom C-band

28.09.2017

A research team of the institute of semiconductor optics and functional interfaces (IHFG) of the University of Stuttgart experimentally verified the generation of polarization-entangled photon pairs in the emission wavelength range of the telecom C-band. The generation of entangled photons, i.e. a non-classical phenomenon which “bounds” the states of two different entities, is a cornerstone for the realization of quantum networks.

Quantum dots are one of the most prominent and promising candidates as non-classical light sources applied in quantum information technology. They have been proven to be able to emit single, indistinguishable and also polarization-entangled photon pairs via the biexciton-exciton cascade.


Schematic representation of a quantum dot emitting polarization entangled photons. The entanglement is here pictorially represented by the transparent connection between the two photons.

Sascha Kolatschek, Universität Stuttgart / IHFG

All these properties have been demonstrated in the NIR regime (i.e. around 900 nm) and here, for the first time, the entangled photon emission was increased up to 1550 nm, key wavelength for fiber-based long-distance classical and quantum communication.

So far the best QD performances have been realized using InAs dots on GaAs platform (naturally emitting at NIR wavelength). This motivated the team of Prof. Dr. Peter Michler to push such a technology up to telecommunication wavelengths.

After long efforts, in close collaboration with the epitaxy team led by Dr. Michael Jetter, it was possible to reach such a milestone, i.e. utilizing In(Ga)As dots to emit telecom-wavelength photons.

The demonstrated entanglement generation in such a system foresees the possibility to extend the unique capabilities reached at NIR up to telecom wavelength. Emission in this regime represents a fundamental skill for fiber-based applications and additionally it is useful for satellite communication, since it marks an atmospheric transmission window.

After the verification of the single-photon nature of the harvested light, moreover an extraordinary low exciton fine-structure splitting (FSS) for most of the investigated quantum dots was measured: indeed, a large FSS inhibits the entanglement generation with high fidelity.

Motivated by this observation, a set of polarization-resolved cross-correlation experiments was performed on an exemplary dot in order to reconstruct the two-photon polarization state that finally reveals the degree of entanglement.

It was found that the detected photons are indeed entangled, which opens the path towards the application of quantum dots in long-distance communication and cryptography schemes. This work represents an important step forward towards the realization of long-distance quantum applications.

Weitere Informationen:

http://dx.doi.org/10.1063/1.4994145

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

More articles from Physics and Astronomy:

nachricht The Fraunhofer IAF is a »Landmark in the Land of Ideas«
15.06.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF

nachricht Delft scientists make first 'on demand' entanglement link
14.06.2018 | Delft University of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

A sprinkle of platinum nanoparticles onto graphene makes brain probes more sensitive

15.06.2018 | Materials Sciences

100 % Organic Farming in Bhutan – a Realistic Target?

15.06.2018 | Ecology, The Environment and Conservation

Perovskite-silicon solar cell research collaboration hits 25.2% efficiency

15.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>