Semiconductors have already revolutionised the world around us through the inventions of the transistor, diode lasers, integrated circuits and sensors. A new wave of semiconductor quantum technologies are finding commercial applications in ultra-secure communications, enhanced imaging, sensing, and possibly even computing and simulations. In all these cases the "quantum advantage" is theoretically proven and experimentally demonstrated, but there is a strong need for a scalable, practical and efficient source of quantum light. Naturally occurring point-like light sources called "colour centres" act as quantum light sources in wide bandgap semiconductors such as diamond, Silicon Carbide, Boron Nitride and Gallium Nitride (GaN) at room temperature. Commercially, GaN now dominates the market for solid state lighting, because it is an efficient and manufacturable material, leading to costs of less than one dollar per LED. However, Gallium-Nitride is also a promising material for quantum light sources as the colour centres within it emit from the ultra-violet to the near infra-red. This wide range means the emission overlaps with minima in the absorption curves of optical fibres (1310 and 1550 nm), transitions in the best atomic quantum memories (near 800nm) and low loss free-space communications in the blue. Furthermore, by engineering heterostructures within the semiconductor it is possible to electrically drive the emitter, rapidly switch the device and design efficiency-enhancing structures. This fellowship will apply manufacturing techniques widespread in the compound semiconductor manufacturing field, such as large area epitaxy and wafer scale processing, to deliver a bright and room temperature quantum light-emitting diode based on GaN. I will use laser lithography, standardised packaging and quality control to ensure the end device is produced in a manner that enables scale up to mass-production, with the full supply chain within the UK. Collaboration with the UK semiconductor industry for growth and packaging of devices, and use of processing facilities installed at Cardiff University, will foster two-way knowledge exchange between industry and academia. My experience of this type of collaboration at Imperial-Agilent and at Toshiba-Cambridge, makes me uniquely well-qualified to manage this interaction. By funding me to devote a significant amount of my time to research for the next 5 years this project will deliver high impact research and build a platform for future UK prosperity and technological know-how.

We will develop novel photonic devices by bonding two different semiconductor substrates with different spacing between atoms. It was very difficult to ensure an excellent quality at the interface, because the atoms cannot connect perfectly, if the lattice spacing is different. We will overcome this problem by making nano-scale tiny trenches to allow atoms to expand for releasing the strain accumulated at the interface. The quality of the interface is very important to make sure to reduce defects in the atomic scale. We will use the interface for making a highly sensitive detector to identify even just single photon (quantum of light), which is impossible to realise with defects due to the noise from additional carriers created by defects. This detector will be useful for future quantum technologies to enable secure communications and powerful commutations. We will also develop a novel laser and high speed optical switches by using this interface. Our project is summarised as follows: 1. Novel Manufacturing Technologies for Enabling Heterogeneous Integrations: We will develop new wafer-scale bonding process technologies to allow excellent interface qualities without defects. Our challenges to overcome the difference of lattice constants and thermal expansion constants for bonded materials. We will accumulate comprehensive knowledge for new bonding techniques. 2. Si/Ge Avalanche-Photo-Diodes and Si/Ge Lasers: The strain engineered interface will enable us to reduce dark currents of Si/Ge Avalanche-Photo-Diodes (APDs) to the level useful for detecting single photons at room temperature. Si/Ge APDs are also useful for LiDAR (Laser Imaging Detection and Ranging). The improved interface quality also enables to achieve lasing of Ge on a Si substrate towards monolithic integrations. 3. Si/LiNbO3 Hybrid Optical Modulator and Second-Harmonic-Generators: We will also bond LiNbO3 on a Si substrate, which allows us to utilise the electro-optic and nonlinear effects of LiNbO3, while keeping the advantages of nanoscale patterning of Si. The hybrid optical modulator with a slot waveguide will be operated at attojoule power consumption by removing the 50 Ohm-termination. The hybrid Second-Harmonic-Generators (SHGs) will convert various wavelengths to generate green and UV lights for much denser data-writing on DVDs. We think our approach will establish a new way of making heterogeneous interface with improved quality. Wafer-scale bonding of a patterned substrate is certainly well-known, but the nano-scale patterning to form perfect bonding in atomic-scale has not yet been achieved, yet. We will accumulate comprehensive knowledge on the developed interface, in terms of various physical parameters such as strains, voids, adhesions, and defects for researchers in nanoelectronics and photonics.

Quantum physics describes how nature links the properties of isolated microscopic objects through interactions mediated by so-called quantum entanglement and that apply not just to atoms but also to particles of light, "photons". These discoveries led to the first "quantum revolution", delivering a range of transformative technologies such as the transistor and the laser that we now take for granted. We are now on the cusp of a second "quantum revolution", which will, over the next 5-10 years, yield a new generation of electronic and photonic devices that exploit quantum science. The challenge is to secure a leadership position in the race to the industrialisation of quantum physics to claim a large share of this emerging global market, which is expected to be worth £1 billion to the UK economy. QuantIC, the UK's centre for quantum imaging, was formed over four years ago to apply quantum technologies to the development of new cameras with unique imaging capabilities. Tangible impacts are the creation of 3 new companies (Sequestim, QLM and Raycal), technology translation into products through licencing (Timepix chip - Kromek) and the ongoing development with industry of a further 12 product prototypes. Moving forward, QuantIC will continue to drive paradigm-changing imaging systems such as the ability to see directly inside the human body, the ability to see through fog and smoke, to make microscopes with higher resolution and lower noise than classical physics allows and quantum radars that cannot be jammed or confused by other radars around them. These developments will be enabled by new technologies, such as single-photon cameras, detectors based on new materials and single-photon sensitivity in the mid-infrared spectral regions. Combined with our new computational methods, QuantIC will enable UK industry to lead the global imaging revolution. QuantIC will dovetail into other significant investments in the Quantum technology transfer ecosystem which is emerging in the UK. The University of Glasgow has allocated one floor of the £118M research hub to supporting fundamental research in quantum science and £28M towards the creation of the Clyde Waterfront Innovation Campus, a new £80M development in collaboration with Glasgow City Council and Scottish Enterprise focussing on the translation of nano and quantum science for enabling technologies such as photonics, optoelectronics and quantum. Heriot-Watt has invested over £2M in new quantum optics laboratories and is currently building a £20M Global Research Innovation and Discovery Centre opening in 2019 to drive the translation of emerging technologies. Bristol is creating a £43M Quantum Innovation centre which already has £21M of industrial investment. Strathclyde University is creating a second £150M Technology Innovation Centre around 6 priority areas, one of which is Quantum Technology. All of these form part of the wider UK Quantum Technology Programme which is set to transform the UK's world leading science into commercial reality in line with the UK's drive towards a high productivity and high-skill economy. QuantIC will lead the quantum imaging research agenda and act as the bond between parallel activities and investments, thus ensuring paradigm-changing innovation that will transform tomorrow's society.