Stockholm university
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Research project Frontiers of topological matter

This project focuses on frontiers of topological matter such as non-Abelian anyons from twists and defects in Moiré heterostructures and topological phenomena in open dissipative systems.

In particular we will consider two complementary frontiers:

(i) Non-Abelian anyons from twists and defects in Moiré heterostructures, including (a) the search for new hosts of non-Abelian fractional Chern insulators and (b) microscopic models of dislocations, primarily in twisted graphene-based multilayer systems, with the goal of identifying ideal premises for a class of non-Abelian anyons known as genons.

(ii) Dissipative topological matter (a) extending our recent work on non-Hermitian topology to the quantum many-body realm and (b) exploring possible applications of non-Hermitian topological sensing.

Albeit being distinct in detail, the parallel theoretical studies of these setups are expected to bring synergy, especially conceptually, by enabling cross-fertilisation between the topics, but also regarding the development of numerical and techniques. Recurring themes include proximity and commensurability effects and non-equilibrium responses to external probes.

Project members

Project managers

Emil Johansson Bergholtz

Professor

Department of Physics
08-553 780 35
Emil J. Bergholtz
emil.bergholtz@fysik.su.se
See profile page for Emil Johansson Bergholtz

Members

Mária Zelenayová

PhD student

Department of Physics
The first year at uni
maria.zelenayova@fysik.su.se
See profile page for Mária Zelenayová

Christopher Gustav Ekman

PhD student

Department of Physics
c_ekman
christopher.ekman@fysik.su.se
See profile page for Christopher Gustav Ekman

News

Department of Physics

Quantum Connections Summer School at Högberga for the thirteenth time

This year's summer school runs from 9 to 22 June at Högberga konferensgård on Lidingö outside Stockholm. About fifty participants will come there to deepen their knowledge. It is a summer school organized for PhD students and postdocs, both theoretical and experimental, in all aspects of quantum limits. Nobel Laureate Frank Wilczek, Professor at Fysikum and Professor Antti Niemi, Nordita are the initiators of the summer school.

Professor Frank Wilczek
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Department of Physics

Emil became a physicist thanks to the research branch

Emil Johansson Bergholtz is Professor of Theoretical Physics at Fysikum. He has been appointed both a Wallenberg Academy Fellow and a Wallenberg Academy Scholar. "It was a coincidence that I got into the subject of physics. I liked solving problems and things that gave resistance. But without the research branch, it is not certain that I would have continued with physics. It was fun and inspiring with the advanced problem solving in the program, says Emil Bergholtz.

Professor Emil Johansson Bergholtz outside AlbaNova. Photo: Gunilla Häggström
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Department of Physics

Non-Hermitian extended midgap states and bound states in the continuum

Maria Zelenayová, PhD student at Fysikum, and her supervisor Professor Emil Bergholtz looked into localization phenomena in non-Hermitian systems that challenge traditional beliefs about states within the energy continuum and those in the gap. The understanding of non-Hermitian extended band gaps and bound states holds significant implications across various domains. In quantum mechanics, this opens up new possibilities for controlling and manipulating the properties of materials. In technology, these insights can be utilized to develop more efficient semiconductors and other advanced materials.

Nodal Phases
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Department of Physics

Particles protected by Braids and Knots

We present a class of systems in which a particle - antiparticle pair cannot annihilate each other after they have moved along a loop, and instead form a new type of composite particle. This occurs in so-called non-Hermitian systems; classical metamaterials or "open" quantum systems that are coupled to the rest of the universe. Lukas Königis a PhD Student at Fysikum and is part of the research group Quantum and Complex Systems.

Flätskyddade topologiska bandstrukturer med oparade exceptionella punkter
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Department of Physics

The Future is Quantum: 20 - 22 February 2023

An emerging field of physics and engineering is quantum technology, encompassing technologies that rely on the properties of quantum mechanics. Quantum computing being one example of these technologies, representing a paradigm shift for computing technology, since it can outperform much more than existing computers. On February 21 at 13:00, in the: Svedberg salen (FD5), AlbaNova, Professor Akira Furusawa from University of Tokyo, RIKEN Center for Quantum Computing will have a presentation with the title THE FUTURE IS QUANTUM - The development of Quantum Computing.

The Future is Quantum
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