Novel Quantum Phases in Unconventional Insulators

Lead Research Organisation: University of Cambridge
Department Name: Physics


My research programme aims to discover new quantum phases. Billions of electrons interact with each other to yield quantum entangled phases of matter with striking new properties distinct from those of single electrons. In 'classical' tuning, phases of matter can transform between each other when their environment is altered using temperature as a tuning tool. For example, ice melts to water, which boils to steam when the temperature is increased. In quantum tuning, parameters other than temperature are used to transform the system between quantum phases at low temperatures. Examples of unconventional phases of matter that emerge from more familiar phases include the striking case where superconductivity - an exotic phase of matter that transports electricity without any resistance to its flow - emerges from a magnetic metal, when high pressures or chemical substitution is applied.

Here, I propose to search for new quantum phases of matter by exploring the little understood regime near correlated insulators, where strong interactions between constituent electrons prohibit electrical transport. Theoretical models and preliminary experiments suggest that strong interaction between electrons in this region offers fertile ground for the discovery of new exotic phases of matter.

In this research programme, we propose to experimentally study two different classes of correlated insulators for the emergence of novel quantum phases. Firstly we explore the copper-oxide family of materials in which superconductivity at high temperatures emerges upon introducing mobile charge carriers in a parent magnetic insulator. We will experimentally explore theoretical predictions for new intermediate phases of matter that emerge in vicinity of strongest superconductivity, proving markedly different from the better-understood case of superconductivity that emerges from a metallic magnet.

Secondly we explore the newly discovered family of unconventional insulators that simultaneously display dichotomous metallic and insulating behaviours. In these materials, despite the bulk of the material exhibiting electrically insulating properties that correspond to virtually immobile electrons, complementary measurements unexpectedly reveal signatures of circulating electron orbits as expected for a bulk metal. Beginning from this unconventional insulating phase of matter, we aim to uncover various novel intermediate phases that emerge enroute to these materials' ultimate transformation to more conventional metals under a combination of applied pressure and high magnetic field.

The discovery of such novel quantum phases of matter, and their ultimate control is crucial for the next generation of quantum electronics based on strongly entangled many-body instead of single electron quantum physics. As such, this study will prove a key element in the development of next generation quantum technologies, a grand challenge identified by the EPSRC. I propose to study a theoretically motivated selection of correlated insulating materials under a combination of extreme conditions of high pressures in strong magnetic fields and low temperatures in this fellowship, and expect to discover new paradigms of novel intermediate phases of matter, and unusual modes of transformation between these unconventional phases of matter.
Title Cavendish Arts Science 
Description Annual fellowships for international artists to spend a year in Cambridge and engage with physicists, producing new artistic outcomes. 
Type Of Art Artistic/Creative Exhibition 
Year Produced 2023 
Impact Moving Image work 'Antiphony' by Logan Dandridge, inaugural Cavendish Arts Science fellow 
Description Studying Research Culture 
Organisation University of Florida
Country United States 
Sector Academic/University 
PI Contribution Working with staff, students and faculty in the Department of Physics at the University of Cambridge to make the environment more welcoming and inclusive for minoritised demographics.
Collaborator Contribution Collaboration using social science methods to understand research culture in Physics.
Impact Multi-disciplinary: social sciences and physics.
Start Year 2022
Description BBC Radio4 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact BBC Radio4 'In Our Time' program on Superconductivity. Broadcast reaches millions of listeners. The broadcast was listed as the top radio program of the week on Radio Times. Several listeners wrote in to me personally and to the BBC later to express their enjoyment of the program, and that it made superconductivity more accessible to general audiences.
Year(s) Of Engagement Activity 2023
Description Invited Talks and Debates at HowTheLightGetsIn, Hay-on-Wye (World's Biggest Philosophy and Music Festival) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Over 500 general audience members attended each of the talks and debates in which I was invited to participate. Several audience members came up to speak to me - from a 10yr old schoolboy to senior academics to artists to investors. The talks and debates have since been posted on Youtube, and have several thousand views each.
Year(s) Of Engagement Activity 2023