The photon is of outmost importance in all areas of quantum technologies as it is the mobile carrier of quantum information. Quantum frequency conversion, i.e. the possibility of specifically changing the frequency or wavelength of the photon, is therefore a key capability in the technical implementation of quantum effects.
The HiFi consortium has dedicated itself to the systematic advancement of quantum frequency converters (QFC) and the required basic technologies. To transmit light quanta in fibre-optic-based networks with low losses, QFC are needed for conversion into the telecom band. In the future, such networks will interconnect quantum processors and registers of different computers over long distances in order to share information and resources confidentially and securely and to increase the computing power of quantum computers.
As part of the HIFI project, Fraunhofer IAF is developing single-frequency semiconductor disk lasers specifically designed as a powerful, low-noise pump source for quantum frequency converters. These will emit in the wavelength range of 2.0 - 2.2 µm and their emission frequency will be actively locked to meet the rigorous requirements of QFCs regarding absolute wavelength accuracy.