New frontiers in topological materials

23 - 24 June 2025 09:00 - 17:00 Hilton Cambridge City Centre Free
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Interwoven string like objects

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
  • When requesting an invitation, please briefly state your expertise and reasons for attending
  • Requests are reviewed by the meeting organisers on a rolling basis. You will receive a link to register if your request has been successful
  • Catering options will be available to purchase upon registering. Participants are responsible for booking their own accommodation. Please do not book accommodation until you have been invited to attend the meeting by the meeting organisers

Enquiries: contact the Scientific Programmes team

Organisers

  • Professor Robert-Jan Slager, University of Manchester, UK

    Professor Robert-Jan Slager

    Professor Robert-Jan Slager obtained his doctorate (2016 with Professor Zaanen) and completed his undergraduate studies, which includes a master's degree in physics (2009 – 2011) and a double bachelor's degree in physics and mathematics (2006 – 2009), at Leiden University. These achievements have, amongst others, been recognised with a national Shell award from the Royal Holland Society of Science and Humanities and a cum laude distinction for his PhD, which involves a special evaluation of a committee of internationally acclaimed researchers and is awarded to approximately 5% of all doctorate students at the University. These studies were followed by postdoctoral positions at the Max Planck Institute for Complex systems and Harvard University, culminating in the acquisition of a principal investigator position at the Department of Physics, University of Cambridge. Per October 2024 he was then installed as Professor of Theoretical Physics at the University of Manchester.

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    Dr F Nur Ünal

    Nur Ünal is assistant professor and Royal Society University Research Fellow at the School of Physics and Astronomy in the University of Birmingham. Previously, she held Marie Skłodowska-Curie and Royal Society Newton Fellowships at the University of Cambridge, postdoc positions at the Max-Planck Institute PKS in Germany and has been an exchange student at Cornell University during her PhD obtained from the Bilkent University. Her work revolves around condense matter systems with a specific focus on quantum simulations with ultracold quantum gases, investigating various novel phenomena including topological systems, out-of-equilibrium dynamics, Floquet, superconductivity, localisation, synthetic gauge fields, fractional quantum Hall and non-Abelian physics.

  • Professor Bartomeu Monserrat, University of Cambridge, UK

    Professor Bartomeu Monserrat

    Bartomeu Monserrat is Professor of Materials Physics at the Department of Materials Science and Metallurgy of the University of Cambridge. He obtained a MSci in Physics from Imperial College London in 2011 and PhD in Physics from the University of Cambridge in 2015. He then held research positions at Rutgers University (2015 – 2017) and Cambridge (2015 – 2019) and joined the faculty at Cambridge in 2020.

    Bartomeu leads a research group that develops and uses computation tools based on quantum mechanics to discover new materials. His work spans a wide range of materials and phenomena, including topological materials, superconductors, and semiconductors for optoelectronic applications. His scientific contributions have been recognised with multiple awards, highlighting the Psi-K Volker Heine Young Investigator Award, the Maxwell Medal and Prize, and the Philip Leverhulme Prize in Physics

    Beyond research, Bartomeu is the creator and co-host of a YouTube channel teaching quantum mechanics to a global audience. The channel has over 25,000 subscribers and has received more than 1.5 million views.

Schedule

08:55-09:00 Welcome by the Royal Society and lead organiser
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 Yan

Professor Bohm Jung Yan

Seoul National University, South Korea

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 Törmä

Professor Päivi Törmä

Aalto University, Finland

10:30-11:00 Break
11:00-11:45 Title to be confirmed
Professor Jacqueline Bloch

Professor Jacqueline Bloch

French National Centre for Scientific Research, France

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 Rechtsman

Professor Mikael Rechtsman

Pennsylvania State University, USA

13:30-14:15 Speaker to be confirmed
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 Felser

Professor Claudia Felser

Max Planck Institute for Chemical Phsyics of Solids, Germany

15:00-15:30 Break
15:30-16:15 Speaker to be confirmed
16:15-17:00 Title to be confirmed
Professor Frank Pollmann

Professor Frank Pollmann

Technical University of Munich, Germany

09:00-09:45 Title to be confirmed
Professor Maia Garcia Vergniory

Professor Maia Garcia Vergniory

Université de Sherbrooke, Canada

09:45-10:30 Title to be confimed
Professor Binghai Yan

Professor Binghai Yan

Pennsylvania State University, USA

10:30-11:00 Break
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-Kurn

Professor Dan Stamper-Kurn

University of California, Berkeley, USA

11:45-12:30 Speaker to be confirmed
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 Beenakker

Professor Carlo Beenakker

Leiden University, The Netherlands

14:15-15:00 Title to be confirmed
Professor Nigel Cooper

Professor Nigel Cooper

University of Cambridge, UK

15:00-15:30 Break
15:15-16:00 Speaker to be confirmed
16:00-16:45 Speaker to be confirmed
16:45-17:00 Panel discussion