Rudolf Römer

Presentation - Rudolf Römer is professor in the Physics Department of the University of Warwick, UK, and associated with Warwick’s Centre for Scientific Computing (CSC) which he led 2005-10. After his undergraduate work in Berlin, he worked in the US (Salt Lake City Utah), India (IISc Bangalore) and Germany (University of Chemnitz). R.A. Römer is an expert in multifractal analysis for the treatment of disorder-driven quantum transitions in 3-D systems. His relevant expertise includes the mathematical physics of exactly solvable quantum many-body systems, applications of network models in the quantum Hall regime, the physics of Anderson localisation (AL) and the interplay of disorder and many-body interactions. In addition, in the last decade, he has been developing simple models of protein flexibility and dynamics as well as studying electronic transport in DNA. Roemer is Fellow of the Institute of Physics and hold a number of fellowships and early-career prizes. He is Visiting Furong professor at Xiangtan University, China and secretary and treasurer of the IOP Theory of Condensed Matter group. Currently, Roemer is editor-in-chief of Physica E “Nanostructures and low-dimensional systems” and on the editorial boards for Scientific Reports and Physics Open as well as Member of the International Advisory Board of the Indian Journal of Physics. From 2011-2018, he was editor of EPL (Europhysics Letters). He is author of more than 170 scientific publications and has record of supervising early career researchers with 6 research assistants, 10 PhD and 8 MSc students since joining Warwick. 

Research project 

One of the central challenges in condensed matter physics is to understand how different phases of matter can arise and how these phases can be characterized. A most simple example is of course provided by the three states of water, i.e. solid ice, liquid water and gaseous vapor. These three phases are distinguished from another by well-defined transitions. In the quantum realm, such phase transition exists as well and give rise to many properties of the world in which we live. Phenomena such as, e.g., magnetism and superconductivity are prime examples which are well know. In recent years, other, so-called quantum phase transitions, have been added to the zoo of transitions.

One such example, disorder-induced localisation, introduced by Anderson already in 1958 but revived due to many recent experiments, embodies the paradigmatic example of a quantum phase transition, i.e. driven by the quantum wave-like nature of matter. Very recently, the novel concept of a dynamical quantum phase transition extends the study of phase transitions to the non-equilibrium regime. Conventionally, the study of phase transitions is tedious because right at the transition, fluctuations from equilibrium dominate, making analytic and numeric treatments challenging. Recent advances in machine learning (ML) and deep learning (DL) promise to offer an alternative route to studying such transitions. The ML/DL approach seems to be able to detect phases and transitions between them directly from the computed quantum states. The states are treated similar to classical “images” where early neural network approaches had already shown to be effective in detecting and extracting information. During the fellowship, I intend to study the application of ML/DL approaches to phases in disordered quantum systems at equilibrium, i.e. Anderson transitions, and non-equilibrium interacting quantum systems after a quench, i.e. DQPTs. Both supervised and unsupervised learning will be applied in both cases.