Generalized quantum optimization algorithms for near-term quantum computing architectures

In a distant future, large-scale, ideal quantum computers will speed up many interesting computational tasks by leveraging a restricted number of fundamental quantum algorithms. However, the rst generation of quantum computers |those that exist now or that we may see in a few years| will be error-prone, hence merely capable of running a restricted set of quantum programmes. In this context, it is pressing to find valuable applications for these machines. Obtaining good solutions to hard optimization problems could be such an application.

The Quantum Approximate Optimization Algorithm (QAOA) is the best-established quantum optimization algorithm for near-term hardware to date. However, as of today, the advantage of QAOA over classical algorithms has remained elusive. More specifically, a series of recent results established significant limitations on the most naive versions of QAOA - though the relevance of these results to the intermediate-scale problems addressable by near-term quantum computers may be questioned.

Starting from the present understanding of the limitations of QAOA, the project will aim at designing generalized versions of the algorithm and assess their performance. Potential applications of these building blocks as shallow approximations of common quantum algorithms will then be explored. Several applications of these approximate algorithms will subsequently be considered, possibly including the enhancement of classical optimization heuristics or algorithms from the variational quantum eigensolver family |which are central to quantum chemistry or material science simulations on a quantum computer.

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.