New frontiers in topological materials

Theo Murphy meeting organised by Professor Robert-Jan Slager, Dr Nur Ünal and Professor Bartomeu Monserrat
Topological materials are an active area of research in all physical sciences. Motivated by the recent synergy with quantum geometry, this meeting will serve as a contemporary event to discuss state-of-the-art advances in theory and experiments. Connecting experts from across condensed matter physics, materials science, and quantum simulators, these discussions will identify novel future research avenues.
Programme
The programme, including the speaker biographies and abstracts, will be available soon. Please note the programme may be subject to change.
Attending this event
- Free to attend and in-person only
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Enquiries: contact the Scientific Programmes team
Organisers
Schedule
08:55-09:00 |
Welcome by the Royal Society and lead organiser
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09:00-09:45 |
How to measure the quantum geometry of Bloch electrons in solids?
Understanding the geometric properties of quantum states and their implications in fundamental physical phenomena is at the core of modern physics. The Quantum Geometric Tensor (QGT) is a central physical object in this regard, encoding complete information about the geometry of the quantum state. The imaginary part of the QGT is the well-known Berry curvature, which plays a fundamental role in the topological magnoelectric and optoelectric phenomena. The real part of QGT is the quantum metric, whose importance has come to prominence very recently, giving rise to a new set of quantum geometric phenomena, such as anomalous Landau levels, flat band superfluidity, excitonic Lamb shifts, and nonlinear Hall effect. Despite the central importance of the QGT, its experimental measurements have been restricted only to artificial two-level systems. In this talk, I am going to present two recent progresses in QGT measurement of Bloch states in solids. First, I will proposed a general method to extract the QGT by introducing another geometrical tensor, the quasi-QGT, who components, the band Drude weight and orbital angular momentum, are experimentally accessible and can be used for extracting the QGT. In the second part, I will report the first direct measurement of the full quantum metric tensors using black phosphorus as a representative material. The key idea is to extract the momentum space distribution of the pseudospin texture of the valence band from the polarisation dependence of angle-resolved photoemission spectroscopy measurement. ![]() Professor Bohm Jung YanSeoul National University, South Korea ![]() Professor Bohm Jung YanSeoul National University, South Korea Professor Bohm Jung Yang is a theoretical condensed matter physicist interested in the study of emergent physics in quantum materials with nontrivial topology and correlative effect. He is interested in (1) the symmetry-based classification of topological phases, (2) the unconventional topological phase transitions and critical phenomena, (3) the search of novel topological superconductors, and (4) the quantum geometry driven physical properties in quantum materials. |
09:45-10:30 |
Quantum geometry and superconductivity
Most superconductors are thermal insulators. A disordered chiral p-wave superconductor, however, can make a transition to a thermal metal phase. Because heat is then transported by Majorana fermions, this phase is referred to as a Majorana metal. We will discuss numerical evidence that the mechanism for the phase transition with increasing electrostatic disorder is the percolation of boundaries separating domains of different Chern number. We construct the network of domain walls using the spectral localiser as a "topological landscape function", and obtain the thermal metal-insulator phase diagram from the percolation transition. ![]() Professor Päivi TörmäAalto University, Finland ![]() Professor Päivi TörmäAalto University, Finland Päivi Törmä is a professor in the Department of Applied Physics, Aalto University, Finland, and has a MSc degree from the University of Oulu, Finland, a Master of Advanced Study degree from the University of Cambridge, UK, and a PhD in 1996 from the University of Helsinki. Her research ranges from theoretical quantum many-body physics to experiments in nanophotonics. Her work has revealed a new connection between quantum geometry and superconductivity that explains why flat bands can carry supercurrent, which is essential in the search for superconductors that work at high temperatures. In her experiments, Päivi has worked on the strong coupling of surface plasmon polariton modes and molecules and her group succeeded in realising the first plasmonic Bose-Einstein condensate. |
10:30-11:00 |
Break
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11:00-11:45 |
Title to be confirmed
![]() Professor Jacqueline BlochFrench National Centre for Scientific Research, France ![]() Professor Jacqueline BlochFrench National Centre for Scientific Research, France After a PhD in semiconductor spectroscopy on the study of quantum wires, Jacqueline Bloch received a permanent position at CNRS in 1994. She initiated a research program on semiconductor microcavities. In 1998-1999, she worked for one year at Bell Laboratories (USA) in the field of ultra-fast spectroscopy in the group of Jagdeep Shah. She defended her habilitation in 2009 and was promoted as CNRS Research Director in 2010. Jacqueline Bloch is presently leading a research group of 8 persons at Laboratory of Photonics and Nanostructures (LPN), in Marcoussis, France. Her group is among the leaders in the field of cavity polaritons with a unique expertise in the study of polariton condensates in microstructured resonators. Jacqueline Bloch is responsible for Nanophotonics at LPN. She is a member of the Research National Panel (Comité National) in charge of the evaluation, promotion and recruitment of CNRS researchers. She is also a member of an ERC panel. Jacqueline Bloch is author of more than 125 publications including 80 peer reviewed articles. |
11:45-12:30 |
Fractional quanitzation in nonlinear optical Thouless pumps
I will present my group's recently experimental work on the fractional pumping of solitons in nonlinear Thouless pumps, using waveguide arrays. Specifically, I will show that the displacement (in unit cells) of solitons in Thouless pumps is strictly quantized to the Chern number of the band from which the soliton bifurcates in the low power regime; whereas in the intermediate power regime, nonlinear bifurcations lead to fractional quantization of soliton motion. This fractional quantization can be predicted from the multi-band Wannier functions associated with the states of the pump. ![]() Professor Mikael RechtsmanPennsylvania State University, USA ![]() Professor Mikael RechtsmanPennsylvania State University, USA Mikael Rechtsman is a Professor of Physics at Pennsylvania State University in the USA, and currently the visiting QuantAlps professor of physics at the Néel Institute of the CNRS in Grenoble, France. His research group carries out both experimental and theoretical research in nonlinear, quantum and topological photonics. He is perhaps best known for the first demonstration of a topological insulators for light. |
13:30-14:15 |
Speaker to be confirmed
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14:15-15:00 |
Topology and chirality
Topology, a well-established concept in mathematics, has nowadays become essential to described condensed matter. At its core are chiral electron states on the bulk, surfaced and edges of the condensed matter systems, in which spin and momentum of the electrons are locked parallel or anti-parallel to each other. Magnetic and non-magnetic Weyl semimetals for example, exhibit chiral bulk states that have enabled the realisation of predictions from high energy and astrophysics involving the chiral quantum number, such as the chiral anomaly, the mixed axial-gravitational anomaly and axions. The potential for connecting chirality as a quantum number to other chiral phenomena across different areas of science, including the asymmetry of matter and antimatter and homochirality of life, brings topological materials to the fore. ![]() Professor Claudia FelserMax Planck Institute for Chemical Phsyics of Solids, Germany ![]() Professor Claudia FelserMax Planck Institute for Chemical Phsyics of Solids, Germany Claudia Felser studied chemistry and physics at the University of Cologne, completing her diploma in solid state chemistry (1989) and her doctorate in physical chemistry. After postdoctoral fellowships at the Max Planck Institute in Stuttgart (Germany) and the CNRS in Nantes (France), she joined the University of Mainz in 1996 as an assistant professor. In 2003, she became a full professor at the University of Mainz and is currently the Director of the Max Planck Institute for Chemical Physics of Solids in Dresden. Claudia Felser in a fellow of the IEEE Magnetic Society, American Physical Society, and Institute of Physics. She is a member of the Leopoldina, the Germany National Academy of Sciences, and acatech, the German National Academy of Science and Engineering. Her research focuses on the design and synthesis, and physical characterisation of new quantum materials, particularly Heusler compounds and topological materials for energy conversion and spintronics. She was inducted into the Hall of Fame of German Research in 2023, and has received several prestigious awards, including the Liebig Medal of the German Chemical Society, the Max Born Prize of DPG and IOP, and the APS James C McGroddy Prize, and the Von Hippel Award. |
15:00-15:30 |
Break
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15:30-16:15 |
Speaker to be confirmed
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16:15-17:00 |
Title to be confirmed
![]() Professor Frank PollmannTechnical University of Munich, Germany ![]() Professor Frank PollmannTechnical University of Munich, Germany Frank Pollmann’s research focuses on a variety of problems in the field of solid state theory. His main focus lies on the study of collective phenomena which arise due to quantum mechanical effects in systems of correlated electrons. He studied physics at Technical University Braunschweig and the Royal Institute of Technology in Stockholm. After completing his PhD at the Max Planck Institute for the Physics of Complex Systems (MPIPKS), Dresden, in 2006, he worked as a postdoctoral researcher at the University of California, Berkeley. From 2011 he headed a junior research group at the MPIPKS. In 2016 he took up an associate professorship appointment at the Technical University Munich. |
09:00-09:45 |
Title to be confirmed
![]() Professor Maia Garcia VergnioryUniversité de Sherbrooke, Canada ![]() Professor Maia Garcia VergnioryUniversité de Sherbrooke, Canada |
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09:45-10:30 |
Title to be confimed
![]() Professor Binghai YanPennsylvania State University, USA ![]() Professor Binghai YanPennsylvania State University, USA Binghai Yan is a theoretical physicist studying quantum materials, including topological materials and chiral materials, at the Pennsylvania State University. After completing his PhD at Tsinghua University in 2008, he worked as a Humboldt postdoc at Bremen University and later at Stanford University. He was a group leader in the Max Planck Institute in Dresden during 2012 – 2016, assistant and associate professor at Weizmann Institute during 2017 – 2024. He joined the Penn State University as a professor of physics in 2025. He was awarded the ARCHES Prize in Germany in 2013, the Israel Physical Society Prize for Young Scientist in 2017 and recognised as a Highly Cited Researcher every year since 2019. |
10:30-11:00 |
Break
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11:00-11:45 |
Quantum simulation of frustrated and topological materials, and of mesoscopic physics, using ultracold atoms
I will present three experiments in the making where we hope to employ ultracold atoms to explore interesting phenomena in condensed-matter and mesoscopic physics. First, I will summarise recent work on transport properties of ultracold atoms within triangular two-dimensional lattices, highlighting effects of geometric singularities at band-touching points and of geometric frustration of atomic motion in flat bands. I will update you on recent efforts to place ultracold Fermi gases in such lattices. Second, I will describe how we hope to use ultracold transition-metal atoms to realise novel states of matter such as topological superfluids, and will present experimental progress in cooling titanium atoms for this purpose. Last, I will describe experiments using atoms trapped in optical tweezer arrays where we return to the study of symmetry breaking transitions related to the Dicke model, but, now, with digital control over the atom number in a distinctly mesoscopic regime. ![]() Professor Dan Stamper-KurnUniversity of California, Berkeley, USA ![]() Professor Dan Stamper-KurnUniversity of California, Berkeley, USA Dan Stamper-Kurn is a Professor of Physics at the University of California, Berkeley, and also a Faculty Scientist in the Materials Sciences Division of Lawrence Berkeley National Laboratory. Together with his research team at Berkeley, Professor Stamper-Kurn is an experimentalist who studies quantum mechanical phenomena in systems composed of ultracold atoms and quantum states of light. Current areas of interest include quantum simulation of geometrically frustrated materials and other condensed-matter systems, symmetry breaking dynamics in mesoscopic systems composed of a small number of atoms, quantum information processing in the neutral-atom platform, and bringing new atomic elements to the ultracold temperature regime. Professor Stamper-Kurn initiated and now directs the Challenge Institute for Quantum Computation, a collaboration centred at several universities across California, which focuses on fundamental scientific and engineering challenges in quantum information science. |
11:45-12:30 |
Speaker to be confirmed
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13:30-14:15 |
Majorana-metal transition in a disordered superconductor: percolation in a landscape of topological domain walls
Most superconductors are thermals insulators. A disordered chiral p-wave superconductor, however, can make a transition to a thermal metal phase. Because heat is then transported by Majorana fermions, this phase is referred to as a Majorana metal. We will discussion numerical evidence that the mechanism for the phase transition with increasing electrostatic disorder is the percolation of boundaries separating domains of different Chern number. We construct the network of domain walls using the spectral localiser as a "topological landscape function", and obtain the thermal metal insulator phase diagram from the percolation transition. ![]() Professor Carlo BeenakkerLeiden University, The Netherlands ![]() Professor Carlo BeenakkerLeiden University, The Netherlands Carlo Beenakker is a theoretical physicist at the Instituut-Lorentz of Leiden Univrsity, where he studies topological states of matter, in particular in view of applications to quantum computing. He is a member of the Royal Netherlands Academy of Arts and Sciences, and a Knight in the order of the Dutch Lion. |
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14:15-15:00 |
Title to be confirmed
![]() Professor Nigel CooperUniversity of Cambridge, UK ![]() Professor Nigel CooperUniversity of Cambridge, UK Nigel Cooper is a condensed matter theorist, working on many-particle quantum systems. His work spans both the traditional solid-state setting of semiconductor materials and the field of ultra-cold atomic gases. He obtained a PhD from Oxford (1994), and held research positions at Harvard, Institut Laue-Langevin (Grenoble), Cambridge and Birmingham (as Royal Society University Research Fellow). He joined the Cavendish Laboratory in Cambridge in 2000, where he is now Professor of Theoretical Physics. He was awarded the 2007 Maxwell Medal and Prize by the Institute of Physics, a Humboldt Research Award (2013) and an EPSRC Established Career Fellowship (2013). |
15:00-15:30 |
Break
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15:15-16:00 |
Speaker to be confirmed
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16:00-16:45 |
Speaker to be confirmed
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16:45-17:00 |
Panel discussion
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