Published: 23 January 2020, 08:14 | By: Christian Helgert
Whether at the supermarket checkout, online banking or when exchanging information between governmental institutions, the transmission of sensitive data via the Internet always requires a certain level of trust. Since all cryptographic systems are based on mathematical principles, they can theoretically be cracked with appropriate computing power. For this reason, ACP scientists together with colleagues from the Technical University of Ilmenau and the Fraunhofer Institute for Applied Optics and Precision Engineering in Jena are developing methods that are based on physical principles and thus offer far safer alternatives. Supported by the Thüringer Aufbaubank, a new research group called "Ultra-wideband high-frequency control of fiber-coupled laser diodes for polarization and time stamp-coded single photons in quantum communication" (short: FastPhoton) has commenced its work on January 1, 2020. The project, led by ACP principal scientists Tünnermann and Eilenberger, is located at the Thuringian innovation center InQuoSens, where researchers from both Thuringian universities develop electronic and nanophotonic solutions for quantum light sources - because these are exactly what the new encryption systems need.
Currently, data is often transmitted using light over fiber optic cables. An enormous amount of photons is used for each bit because the particles can be detected and amplified so well. "But if the information can be transmitted in individual photons, then the quantum properties of the particles come into play, which enable purely physical encryption methods," explained ACP principal scientist Eilenberger. "In terms of security, this means an enormous qualitative improvement. Because a quantum-decoded photon can only be measured once and can therefore only be read by one recipient, external access would not remain undetected. This is how security becomes measurable."
The physical principles for such a procedure have been known and proven for several decades. As part of the research group, the scientists want to focus particularly on the development, improvement and integration of suitable single photon sources that produce the necessary photons with precisely defined quantum states. Despite the considerable progress in the field of quantum communication, ACP scientists are expecting that it will take a few years before end users exchange information in this way. But then, systems based on single photons could be used as a safe alternative for the transmission of highly sensitive data.