The emerging quantum technologies will have a huge impact on society, disruptive changing the way information is processed and distributed. Quantum cryptography is a main concern for society, since by this technology any attack on the privacy of communication can be detected and, thus, misuse of private data impeded. For quantum cryptography, the efficient generation of single photon states is a vital task. Current approaches are bulky and expensive with low generation rates. To pave the way for widespread applications, the lessons learned from classical, Silicon- based information technology have to be recalled: devices need to be robust, highly integrated and cheap to be practically applicable. By far the densest and most robust integration of various functionalities is achievable with Si standard CMOS technology at extremely low costs. Thus, CUSPIDOR aims on developing a novel integrated quantum optical platform relying on a fully CMOS-compatible technology, which is able to provide sources of deterministic single photons.
These photons will be generated at the telecommunications wavelengths, so that the existing elaborate telecommunication networks can be used for quantum communication.
A newly developed type of silicon-germanium quantum dots (SiGe QDs) will be used as quantum emitter, showing telecom-wavelength emission up to and above room temperature. These QDs will be optimally and deterministically coupled with nano-photonic resonators for further enhancement of the single photon emission rate. This coupling will be achieved by site controlled QD growth in combination with precisely aligned, lithographically defined photonic crystal resonators, allowing upscaling and a straight forward implementation of areas of identical single photon sources. By implementing these sources in lateral p-i-n diodes, electrically triggered single photon emitter will be developed.
In addition, the QDs will be used in CUSPIDOR to provide a strong optical nonlinearity for the realization of a single photon source via the implementation of an on-chip photon blockade. Such devices suppress photon transmission as long as a previous photon is in the device. Thus, a stream of single, temporally evenly separated photons leaves the device upon interaction with a laser beam. Quantum interference in coupled photonic crystal resonators increases the system’s sensitivity providing a practical path to the first integrated photon blockade device- a “holy grail” of the Quantum photonics community, and provide opportunities for coherent quantum communication protocols not possible with a single quantum dot.
The project will create a strong team of quantum photonics researchers proficient with material design and growth, advanced CMOS processes and nanophotonics design. A firm basis of design skills and fabrication expertise will be established that will provide a springboard for further innovation and the exploitation of quantum light sources.
CUSPIDORS final target is a demonstrator for a compact, integrated, and flexible source of quantum states of light ready for prototyping.
