Quantum Computing with Superconducting Gatemon Qubits

Superconducting transmon qubits are an attractive platform for building a prototype quantum computer comprising ~100 qubits. In order to go beyond this and build quantum computers powerful enough to break secure encryption or simulate small molecules, it will be necessary to improve coherence and scalability. Gatemon qubits based on III-V semiconductors are a recently innovated voltage-controlled transmon that offers advantages with scaling, but their performance is currently limited by microwave losses. In order to improve performance we will study loss mechanisms in III-V structures comprising Al/Nb/InP by measuring the power, temperature and time-dependence of quality factors. Initial measurements will be performed at the National Physical Laboratory. We will also explore voltage-controlled semiconductors that can be grown on low-loss Si substrates, for instance, graphene or V-VI topological insulators. The strong spin-orbit interaction in the latter also makes it possible realise Majorana physics and and one aim is to test for topologically-protected relaxation times in a Majorana transmon-MRC.

The main impact of the proposed Hub will be in training quantum engineers with a skillset to understand cutting-edge quantum research and a mindset toward developing this innovation, and the entrepreneurial skills to lead the market. This will grow the UK capacity in quantum technology. Through our programme, we nurture the best possible work force who can start new business in quantum technology. Our programme will provide multi-level skills training in quantum engineering in order to enhance the UK quantum technologies landscape at several stages. Through the training we will produce quantum engineers with training in innovation and entrepreneurship who will go into industry or quantum technology research positions with an understanding of innovation in quantum technology, and will bridge the gap between the quantum physicist and the classical engineer to accelerate quantum technology research and development. Our graduates will have to be entrepreneurial to start new business in quantum technology. By providing late-stage training for current researchers and engineers in industry, we will enhance the current landscape of the quantum technology industry. After the initial training composed of advanced course works, placements and short projects, our students will act as a catalyzer for collaboration among quantum technology researchers, which will accelerate the development of quantum technology in the UK. Our model actively encourages collaboration and partnerships between Imperial and national quantum tehcnology centres and we will continue to maintain the strong ties we have developed through the Centre for Doctoral Training in order to enhance our on-going training provisions. The Hub will also have an emphasis on industrial involvement. Through our new partnerships students will be exposed to a broad spectrum of non-academic research opportunities. An important impact of the Hub is in the research performed by the young researchers, PhD students and junior fellows. They will greatly enhance the research capacity in quantum technology. Imperial College has many leading engineers and quantum scientists. One of the important outcomes we expect through this Hub programme is for these academics to work together to translate the revolutionary ideas in quantum science to engineering and the market place. We also aim to influence industry and policy makers through our outreach programme in order to improve their awareness of this disruptive technology.