Breakthrough in ultra-secure communications through fiber optics is reached in Chile

*Foto_1Theft of passwords is closer to being a thing of the past thanks to the work developed by researchers of CEFOP-UdeC. The prestigious magazine Physical Review Letters published this work in its latest issue, which means we are one step closer towards communications security through fiber-optic networks.

Theft of information, such as passwords that you use to access your email account, is one of the major headaches in this era. The confidence of users decreases more and more with leaks, for example that the National Security Agency of the United States (NSA) listens in with various cryptography systems in use worldwide. How do we face this? Quantum communications is the answer, although it has a “however“.

Researchers from the Center of Optics and Photonics at the University of Concepción (CEFOP-UdeC), from the Faculties of Engineering, Physical Sciences and Mathematics, have taken an important step in making quantum communications a reality, leaving behind those “howevers”, that have to do mainly with the stability of communication over long distances. This advance was outstanding and was published by the prestigious scientific journal Physical Review Letters.

Dr. Guilherme Xavier, part of the research team for this project (Gustavo Lima, Miguel Figueroa, Gonzalo Carvacho, Jaime Carine, Gabriel Saavedra, Alvaro Cuevas, Jorge Fuenzalida, Felipe Toledo, Adán Cabello, Jan-Akelarsson and Paolo Mataloni), explains that they have shown the possibility of making ultra-secure communications based on quantum entanglement in optical fibers. “It means that a gap was definitely closed – related to the operation of detectors – from several previous demonstrations of quantum communication systems based on quantum entanglement in optical fibers. We took an important step towards the implementation of these systems in commercial optical networks,” the researcher explained.

El Dr. Guilherme Xavier, parte del equipo investigador de este proyecto (Gustavo Lima, Miguel Figueroa, Gonzalo Carvacho, Jaime Cariñe, Gabriel Saavedra, Álvaro Cuevas, Jorge Fuenzalida, Felipe Toledo, Adán Cabello, Jan-ÅkeLarsson y Paolo Mataloni), explica que en este trabajo han demostrado la posibilidad de realizar comunicaciones ultra seguras basadas en el entrelazamiento cuántico a través de fibras ópticas. “Significa que se cerró definitivamente una brecha –relativa al funcionamiento de los detectores- de varias demostraciones anteriores de sistemas de comunicación cuántica basados en entrelazamiento cuántico a través de fibras ópticas. Dimos un paso importante para la implementación de estos sistemas en redes ópticas comerciales”, explica el investigador.


For the measurements, carried out in the quantum communications laboratory of CEFOP-UdeC located at the Faculty of Engineering, a pair of entangled photons (light-based quantum systems) were generated. One of them was sent by the optical fibers network of the University to the atmospheric optics laboratory, located on one of the hills of the University, while the second photon stayed in the original laboratory.

According to Dr. Xavier, “We did a joint measurement on them to verify that entanglement is preserved, and this ensures that communication can be safe. For this, a technological challenge was the development of a system of phase stabilization, to preserve the entanglement over long distances, 3.7 kilometers, such as in this experiment. The challenge is that the path differences at that distance should be less than 100 nanometers.” This means that if Chile is traversed throughout its length, by two different paths, the difference of the paths should be less than the thickness of a hair.


Such networks are perfect for sensitive communications in financial, diplomatic and even military areas. In short, this technology will enable the development of secure communications systems where the user does not have to make any assumption regarding the reliability of devices used. Entanglement-based quantum communication systems do not need to make these assumptions.

The next step for this group of researchers is the construction of a new source of photons that are more optimized for current fiber optics communications systems to increase transmission distance, and, at the same time, the execution of a distribution session of automated cryptographic passwords with this new system.

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