Lightcones in quantum matter

Quantum theory is perhaps our most successful theory of Nature - it describes the microscopic laws underpinning the dynamics of atoms and subatomic particles with truly remarkable precision. One might think that, armed with these laws, we should have no problem predicting the phenomena and behaviour that emerges from the motion and interaction of these particles. But this is not the case! The mathematical structure of quantum theory, in general, makes it very hard to calculate what happens when lots of quantum particles interact together, even if one uses the world's most powerful supercomputers.

A proposed solution to this problem is to use quantum particles themselves to do the calculation - to build a quantum computer, which could simulate the quantum world in far greater detail than is currently possible. But we still need to understand (at least relatively well) how the large, many-particle quantum systems needed to build such a device behave in order to realise this.

The goal of this PhD project will be to develop new algorithms - for classical and quantum computers - which can efficiently calculate properties of many-body quantum systems. In particular, I will focus on the problem of characterising how quickly information can spread out in different quantum systems. This may help us benchmark and test quantum computers more robustly, study protocols for correcting errors in quantum computers, and tackle open problems in many-body quantum physics - such as understanding interesting phase transitions between states of many-body quantum systems with drastically different behaviour - in a new way.

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.