Optoelectronics/Quantum Devices

Controlled fabrication of complex multiphoton states in miniaturised semiconductor quantum devices

The overall goal of the project is the fabrication of multiphoton states via semiconductor quantum devices. Such multiphoton states are of highest interest in the field of photonic quantum technology. So-called N-photon N00N states allow highly precise phase measurements beyond classical limits. While single photons with high quality and emission rate can be generated today via highly optimised quantum dot light sources, the generation of multiphoton states and the application of these quantum states are still in their infancy. Due to the diverse application possibilities and extremely interesting questions, current work is now increasingly turning its attention to this attractive field of quantum nanophotonics, which has so far only been researched to a limited extent. Corresponding work shows the attractiveness and feasibility of corresponding concepts. However, studies and applications going beyond this require a deeper understanding of the processes involved and better technological control of the structures themselves.

Against this background, in the present project individual semiconductor quantum dots are specifically embedded in microtowers and microlenses via deterministic nanofabrication methods and systematically controlled externally. The component integration thereby increases the light-matter interaction and the photon decoupling efficiency. The structures will be completed by piezo elements to control the spectral properties of the quantum dot microstructures conveniently and very reproducibly via voltage variation. This technological work, together with sophisticated quantum optical methods such as two-photon resonant excitation, form the necessary basis for the complex experimental work planned.

The physical questions focus on multiphoton generation via the biexciton-exciton cascade of semiconductor quantum dots. The rich physics of this cascade and the resonant driving of the transitions by two-photon excitation should allow, for example, to generate polarization-entangled photon pairs and N=4 NOON states, which are also to be generated via the resonantly driven biexciton-exciton cascade. Furthermore, it is planned to perform Franson interferometry using such photon pairs in order to prove the violation of Bell's inequality.

Quick Info

Project startSeptember 2018
Funding sourceDeutsche Forschungsgemeinschaft (DFG)
Funding IDRE 2974/18-1