The quantum limits of micromachined gravity sensors

"This project will investigate the ultimate performance achievable with a micromachined gravity sensor. The goal is to develop an existing 0.25 ng/rtHz silicon sensor, the highest resolution presently achieved by an inertial silicon sensor by some margin, and previously delivered to NASA as a Mars microseismometer, but with application to gravity sensing. Although MEMS technology is generally limited by thermodynamic noise, either in the electronics or the suspension, we have now pushed these limits low enough that it appears that quantum effects are setting the ultimate performance.

The first stage of this project is to probe the limiting role that quantum mechanics is playing in these sensors. It is believed that surface states on the electrodes of our position transducer may be playing an important role. If so, microfabrication may be able to minimise the contribution through an engineered approach to dimensionally constraining these states. This work might suggest a way to minimise the "patch" effect, a problematic noise source for ultrahigh precision sensors.

The MSc work will involve modelling using finite element analysis of the electron states, and in particular the effect of the variation of surface potentials on the measurement of capacitance and producing a first principles estimation of the noise floor. This modelling will be extended to consider different electrode geometries. With the fundamental limitations better quantified, the PhD can proceed to investigate design trades to optimise sensor geometries, and then to build and lab test these under a range of possible deployments. "

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.