In recent years, quantum optics has revolutionized the way we think about computing and communication. The experimental demonstration of quantum teleportation, quantum key distribution for secure communication and many other exciting achievements in the field of quantum computing will enable novel applications that were considered to be impossible only a few decades ago.
At the heart of all these systems are single photon sources (SPS): laser-like systems that emit a single photon at a time, unlocking the quantum nature of light. One demonstrated approach to realize single-photon sources is by exploiting non-linear optical effects such as parametric down-conversion or four-wave mixing using exotic materials with large second order nonlinearity. However, strong table-top pump lasers are typically required resulting in expensive and bulky configurations. In addition, the realized SPS are non-deterministic, owing to the spontaneous nature of the non-linear effects, which is hampering scalability in practical implementations. Alternatively, in the past 15 years, semiconductor quantum dots (QD) were shown to emit single photons when strongly coupled to the resonant mode of a high-quality optical cavity, opening a path towards compact, integrated and deterministic single-photon sources. The latest quantum dot-based single-photon sources are moving closer to the ideal single-photon source and have opened new possibilities for large quantum optical systems.
In the proposed work, the PhD candidate will explore and pioneer the potential to realize waveguide-coupled QD SPS devices, leveraging imec’s deep expertise in wafer-scale epitaxial growth of laser-grade III-V materials on Si coupled with imec’s deep know-how in silicon photonics. High-quality III-V waveguide nano-ridges, directly grown on 300 mm silicon substrates applying metal organic vapor phase epitaxy (MOVPE), will be used as a base structure on which to grow high-quality single-QD emitters. Following the development and optimization of the epitaxial growth processes, device processing steps will be carried out to embed the QD in high-quality optical cavities, realizing high-performance on-chip SPS. In addition, the III-V nano-ridges can also be coupled to a silicon photonic circuit which will enable the integration of an efficient and deterministic single photon source directly with the quantum optical system on a single chip having the size of a fingernail. Such a tight integration scheme paves the way for the wide-spread deployment of quantum optic systems.
The student will perform an in-depth study of the involved physical processes to gain insight into the possibilities and limitations of such a system. This activity encompasses a literature review, epitaxial growth development via MOVPE and deep structural and optical characterization of the realized QDs. Depending on the progress and success of the growth development, the student could use the knowledge assembled in the first phase to fabricate integrated single photon emitters.
Required background: Master in materials science, physics, electronic engineering or photonic engineering
Type of work: 50% experimental work + data analysis, 20% theoretical study + modelling, 15% literature study, 15% dissemination
Supervisor: Dries Van Thourhout, Bernardette Kunert
Daily advisor: Bernardette Kunert
The reference code for this position is 1812-33. Mention this reference code on your application form.