Quantum physical phenomena enable novel applications in science and technology that will lead to significant improvements in information processing in the long run. Quantum communication in particular is on the verge of technological maturity for real application scenarios and can be implemented by means of Quantum Key Distribution (QKD). It can address concrete needs for increased data security in new digital business fields such as the smart grid, personalized medicine or microtransaction banking and can become a locational advantage of a data-driven economy. However, current approaches to quantum communication only achieve low electro-optical integration density and key rates in the low kbit range. Comparable to modem transmission in the early days of the Internet, this results in high costs per system and per data unit, in this case per key, thus limiting important applications. Significant development potentials exist along the entire communication chain of a.) increasing the drive frequency of photon sources such as DFB laser diodes or VCSELs and modulators as well as electroplasmonically pumped single photon emitters, b.) reducing the transmission losses of the quantum mechanical states of the free beam and fiber links by novel modulation formats and c.) reducing the time resolution of single photon detectors. It is interesting to note that the efforts from the field of telecommunications for high-frequency optical data transmission can only be applied to a limited extent, since e.g.: the generation of the fragile quantum states requires an extreme degree of precision. For sources this requires extremely good extinction parameters and an adaptation of the modulation formats to the quantum mechanical paradigm of amplifier-free transmission paths.
