We are advertising for two PhD opportunities in the Prentice Group in the general area of materials for quantum technology. Details of these projects are listed below, and can also be found on FindAPhD.

These projects have no specific funding attached to them, but there are many funding opportunities available for PhDs at Manchester, for both home and overseas students (see Join us for more details). We particularly encourage applications from those who identify as belonging to a group under-represented in science and engineering; there are also more funding pathways available for such applicants. Self-funded applications are also very welcome.

All applications should be made through the University of Manchester online system. If you’re interested in one of these projects, please do get in touch with Joe!

---

Engineering phonon chirality with crystal defects from first principles

Chirality – where an object is not superimposable on its mirror image – is a fundamental property relevant in fields from biology to particle physics. Crystal structures of materials can be inherently chiral, but it is also possible for the vibrations of the atoms to exhibit chirality, even if the structure itself is not chiral. Such vibrations are known as ‘chiral phonons’, and have been the subject of intense research since being identified a decade ago. Many, although not all, chiral phonons carry angular momentum, which makes them useful for many potential applications, including in valleytronics, quantum technology, nanomechanics, and even dark matter detection.

Despite this rapid progress, however, there are still gaps in our understanding. One such gap concerns how defects influence chiral phonons. As defects are ubiquitous in real materials, understanding this is vital for technological applications. Defects can often significantly affect the phonons of a material, by forming localised phonon modes, for example; certain defects can also induce local structural chirality. The interaction between defects and chiral phonons is still relatively underexplored. This work lends itself very well to atomistic modelling, as we can control what defects are in the system, and obtain atomistic information about vibrational motion.

In this PhD project, we will make use of cutting-edge computational materials modelling methods, including (linear-scaling) density functional theory, quantum embedding, and machine learning potentials, to systematically investigate how the presence of various defects affects phonon chirality. Initially, we will focus on inherently chiral materials, such as α-quartz, cinnabar, and α-cristobalite, before moving on to consider chiral defects in achiral systems, such as screw dislocations, chiral substitutions, and interstitials. This will provide insight into how the angular momentum, localisation, and frequency of chiral phonons can be modified, and how chiral phonons can be induced in achiral systems, helping to push technological applications of chiral phonons towards reality.

This project would suit a student with an interest in computational modelling – experience in modelling would be beneficial, but not necessary.

---

Understanding point defects in wide-gap semiconductors for quantum technology applications from first principles

The success of the next generation of quantum technology will fundamentally depend on the materials used to it. One of the leading classes of materials for these applications is point defects in crystalline solids, particularly wide-band gap semiconductors, thanks to their stability, relatively long spin coherence lifetimes, and ability to operate near room temperature.

The spin coherence lifetime is influenced by the presence of spin-carrying isotopes in the host material. Unless the host is enriched, this will depend on the natural isotopic abundance of the elements in the host. Some wide-gap semiconductors therefore have a much more favourable abundance of spin-carrying isotopes; however, many such materials are underexplored.

In order for point defects in these systems to be used in applications, suitable candidates must first be identified, before then considering their interaction with the environment in the host material during and after fabrication. First principles modelling is a vital tool in this endeavour, allowing us to establish which defects are energetically favourable, how mobile they are, their excited state properties, and the influence of environmental effects on these properties. Combining this data together allows us to identify candidate systems, and to computationally characterise novel defects, using theory to guide experiment and industry.

In this PhD project, we will make use of cutting-edge computational methods, including linear-scaling density functional theory (LS-DFT), quantum embedding, and machine learning potentials, to systematically characterise candidate point defects in wide-gap semiconductors with long spin coherence times, and explore this vast configurational space for novel defects. The initial focus will be on defects in Ca-containing compounds (e.g. CaO, CaS, Ca3WO10), but will expand to explore other hosts and implanted ions. The project will provide insight into the fundamental physics of these systems, and their robustness against external perturbations. An important aspect will be comparing against experiment by collaborating with world-leading experimental groups, including the Curry group (Manchester).

This project will suit a student with an interest in computational modelling and/or materials for quantum technology. An interest in materials modelling software development would be beneficial, but not necessary.