Minimally-controlled quantum information processing

In order to implement a quantum algorithm, gate-based quantum computing uses a significant number of control pulses for separate unitary operations. This project aims to perform quantum computation with a minimal number of control pulses. We investigate theoretically whether Hamiltonian couplings can be engineered such that the natural system dynamics can perform useful computation.

Ultimately, we propose a von Neumann architecture for quantum computation in the NISQ era. We want to examine whether engineered spin chains, equivalent to 1-dimensional arrays of interacting qubits, can be used as processing units for quantum algorithms and data-buses for quantum state transfer. In this design, the processing unit can be viewed as a quantum automaton, where a spin is initialised and then evolves with natural dynamics to a final state, giving the result of a computation. Specifically, we consider the quantum Fourier transform (QFT) with more than 3-qubits, and then look to extend this idea to other algorithms. We also investigate spatial search using quantum walks that can be realised in 1-dimensional spin chains with long-range interactions. These algorithms might be possible in higher-excitation subspaces with some potential advantages.

We aim to collaborate with experimental groups, primarily in ion-trap arrays for spatial search and in quantum dot architectures for implementing other quantum algorithms, such as QFT, or quantum communication schemes with minimal control.

The first and most important impact of our Centre will be through the cross-disciplinary technical training it provides for its students. Through this training, they will have not only skills to control and exploit quantum physics in new ways, but also the background in device engineering and information science to bring these ideas to implementation and to seek out new applications. Our commercial and governmental partners tell us how important these skills are in the growing number of people they are hiring in the field of quantum technologies. In the longer term we expect our graduates to be prominent in the development of new technologies and their application to communication, information processing, and measurement science in leading university and government laboratories as well as in commercial research and development. In the shorter term we expect them to be carrying out doctoral research of the highest international quality.

Second, impact will also flow from the students' approach to enterprise and technology transfer. From the outset they will be encouraged to think about the value of intellectual property, the opportunity it provides, and the fundraising needed to support research and development. As students with this mindset come to play a prominent part in university and commercial laboratories, their common background will help to break down the traditional barriers between these sectors and deliver the promise of quantum technologies for the benefit of the UK and world economies. Concrete actions to accelerate this impact will include entrepreneurship training and an annual CDT industry day.

Third, through the participation it nucleates in the training programme and in students' research, the Centre will bring together a community of partners from industry and government laboratories. In the short term this will facilitate new collaborations and networks involving the partners and the students; in the long term it will help to ensure that the supply of highly skilled people from the CDT reaches the parts of industry that need them most.

Finally, the CDT will have a strong impact on the quantum technologies training landscape in the UK. The Centre will organise training events and workshops open to all doctoral researchers to attend. We will also collaborate with CDTs in the quantum technologies and related research areas to coordinate our efforts and maximise our joint impact. Working in consort, these CDTs will form a vibrant national training network benefitting the entire UK doctoral research community.