Assuring quantum randomness from simple optical measurements

Random numbers are a fundamental part of science and technology, being especially relevant for
cryptography, gaming, simulations or statistics. Quantum random number generators (QRNG) rely on
the intrinsic randomness of quantum mechanics to generate true and unpredictable random numbers,
unachievable from the classical physics perspective. Methods and protocols to certify and quantify
the randomness in the output of a quantum system are a current subject of intensive research. In
this thesis, we focus on the emergent field of quantum random number generation proposing two semidevice-
independent schemes to harvest quantum entropy while discussing in detail their strengths and
weaknesses. With the purpose of developing a certification protocol for these approaches, we thoroughly
study the implementation of the photodetector and the possible vulnerabilities it might introduce in
our approaches. Finally, we perform a proof-of-concept experiment to demonstrate the feasibility of
the suggested schemes and experimentally investigate the correctness of the derived theoretical models.
The results for these experiments revealed a satisfactory agreement with the theory and enabled us to
extract 1.58 bits of quantum randomness per sample with an 8-bit digitisation out of our QRNG.

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.