The transmission and processing of information in many quantum computing, comms. and sensing systems rely on the use of photons. Most state-of-the-art systems demonstrations make use of free-space beam paths and bulk optics components to transport photons between nodes and employ efficient material nonlinearities in crystals to create interactions between them. These systems have been crucial in the demonstration of proof-of-concept experiments, but are not well suited to scaling beyond a few photon-photon path interactions, limited by the size of the components and complexity of their arrangement.

By moving to an on-chip environment, the mechanical stability, complexity and yield of photonic integrated circuits (PICs) enables the scaling of these systems by orders of magnitude1. Nevertheless, there are a number of open challenges that need to be overcome to meet the strict performance requirements of quantum systems in terms of loss, efficiency and operating wavelength range. In particular, many of the functions required on chip, including non-linear photon interactions or high-efficiency photon generation and detection, require different materials and have been developed at different wavelengths (e.g. high efficiency silicon detectors in the visible and low-loss circuitry and non-linear optics in the IR spectral range).
In this project the student will develop a new platform for non-linear photonics on-chip at UV to visible wavelengths. PIC platforms in Al2O3, and III-N materials will be fabricated in-house in the Technology and Innovation Centre cleanroom to produce PICs with low-loss and high-channel count. Integration of silicon single photon detectors and non-linear optical resonators with these PICs will be achieved using a custom, nanometre scale accurate, transfer print system developed by our group2. Through the heterogeneous integration of multiple, micron scale components on-chip, the student will realise photon transmission and processing circuits in mm2 areas that can be deployed in communications, computing and sensing applications3-5. By advancing this technology into the UV and visible range of the spectrum, the project will provide much needed hardware to interface scalable optics with solid state quantum emitters/memories on-chip, or for scalable beam projection systems for multi-site atom/ion trapping/addressing applications.

The student will develop skills in numerical simulation of guided-wave photonics including Finite Difference Time Domain and Eigenmode modelling, to design efficient optical resonators, power-couplers and material-to-material transitions. The student will be trained in the University Cleanroom labs to translate these designs into photonic chips using state-of-the-art laser lithography and reactive ion etching tools. They will develop world leading skills in transfer printing integration using the unique toolset at Strathclyde developed by our group, enabling direct pick-and-place of micron-sized optical components onto PICs. Finally, measurement of the chips will be carried out optical labs hosting advanced laser sources, single-photon detection systems and high-speed metrology equipment. The student will also benefit from complementary facilities in the Fraunhofer UK labs.

In addition to the CDT training programme, the student will be part of a cohort of researchers at the Institute of Photonics and will be supported in the development of professional skills in research communication, project planning and will have access to regular technical seminars, journal clubs and group social activities.