Aalto Quantum Physics Seminars (Hybrid). Speaker: Dr. Cécile Repellin (CNRS, Laboratoire de Physique et Modélisation des Milieux Condensés, France)
Correlated Quantum Materials (CQM)
The Correlated Quantum Materials (CQM) group focuses on theoretically studying emerging quantum phenomena in solid-state systems. In particular, we are highly interested in materials where electronic correlations and topology yield exotic physics such as symmetry broken states, topological excitations and ultimately emerging fractionalized particles. A central part of our research focuses on two-dimensional materials, including graphene and two-dimensional magnetic materials. In our group, we aim to provide theoretical routes to engineer exotic states of matter in twisted van der Waals systems, including twisted graphene multilayers. As specific goals, we aim to unveil potential routes to engineer unconventional superconductors, quantum spin liquids, topological states and fractionalized matter in van der Waals materials. We are also developing new methodologies to treat quantum many-body fractional matter using both neural-network and tensor-network quantum algorithms. Besides our purely theoretical research line, we often work in collaboration with experimental groups studying quantum materials in general, and two-dimensional materials in particular.
Current main research lines:
Emergent quantum phenomena in van der Waals materials
Van der Waals heterostructures provide an outstanding platform to engineer elusive quantum phenomena, by exploiting materials engineering, twist engineering and proximity effects. We are interested in developing new theoretical routes to exploit the flexibility of these materials to create exotic physics not accessible in conventional compounds. On the theory side, among others, in this line, we recently showed how to generate artificial gauge fields, tunable frustrated magnets, and controllable correlated states, and heavy-fermion phenomena in twisted graphene multilayers. In collaboration with experimental groups, we recently showed how to design many-body heavy-fermion systems in van der Waals multialyers, how to probe magnetic excitations in van der Waals magnets, and how to probe crystal field effects in twisted graphene multilayers.
Interacting & quasiperiodic topology and exotic excitations in condensed matter systems
The interplay of strong electronic interactions and topology represents one of the most exciting lines in condensed matter, opening venues to engineer quantum excitations not present in nature, such as fractionalized excitations, supersymmetric excitations and emergent topological states. Among others, in this line, we recently showed how to create Chern insulators by exploiting interactions in topological metals, how to engineer topological excitations by exploiting quasiperiodic many-body states, how to create solitonic excitations between quantum disordered magnets and superconductors, and in collaboration with an experimental group how to generate and probe critical quasiperiodic states. The methodologies that we develop are implemented in freely available in an open source library to study electronic, interacting and topological properties of tight binding models.
Engineering and detecting unconventional superconductivity
Unconventional superconductors are highly pursued for their exotic quantum properties, and ultimately for their potential for topological quantum computing. However, these states are extremely rare to find and detect in nature, with very few compounds showing signatures of such physics. Among others, in this line, we recently showed how to create a topological superconductor with antiferromagnets, how to detect the interplay between atomic defects and moire superconductivity in twisted graphene bilayers, how to detect non-unitary multiorbital superconductors in angle-resolved photo-emission spectroscopy experiments, and how moire patterns promote topological superconducting states.
Quantum neural-network and tensor-network algorithms
Understanding exotic phenomena in quantum systems often requires developing new theoretical methods for model analysis and prediction. In particular, we are especially interested in developing new methodologies to understand and detect quantum-many body phenomena using a new family of quantum network algorithms. In this direction, recently we demonstrated how to power-up many-body methodologies with neural-network algorithms, how to detect topological quantum matter with neural-network algorithms, how to compute dynamical topological excitations in many-body systems using kernel polynomial tensor-network methods, how to exploit tensor-network algorithms to predict quantum many-body criticality. Most of the methods we design are also implemented in freely available open source libraries we develop to solve quantum many-body problems with tensor networks.
Current group members:
- Jose Lado: Assistant professor
- Guangze Chen: Doctoral candidate
- Maryam Khosravian: Doctoral candidate (co-supervised with Prof. Peter Liljeroth)
- Rouven Koch: Doctoral candidate
- Pascal Vecsei: Doctoral candidate (co-supervised with Prof. Christian Flindt)
- Marcel Niedermeier: Doctoral candidate (co-supervised with Prof. Christian Flindt)
- Vilja Kaskela: MSc Student (co-supervised with Dr. Adolfo Fumega)
- Timo Hyart: Research Fellow
- Faluke Aikebaier: Visiting postdoctoral researcher (from the group of Prof. Teemu Ojanen at Tampere University)
- Adolfo Fumega: Postdoctoral researcher (co-supervised with Prof. Peter Liljeroth)
- Netta Karjalainen: Research assistant (co-supervised with Prof. Theo Kurten)
- Zina Lippo: Research assistant
Former group members
- Mikael Haavisto: Research assistant (co-supervised with Dr. Adolfo Fumega)
- Pramod Kumar: Postdoctoral researcher
- Valerii Kachin: Research assistant (co-supervised with Prof. Teemu Ojanen and Dr. Timo Hyart)
- Heikki Systä: Research assistant (co-supervised with Prof. Päivi Törmä)
- Pinja Hirvinen: Research assistant
- Timo Kist: Research assistant (co-supervised with Prof. Christian Flindt)
- Senna Luntama: Research assistant (co-supervised with Prof. Päivi Törmä)
Research Group Members
Recent Events & News
Researchers have demonstrated a new technique to measure the quantum excitations in superconducting materials with atomic precision for the first time. Detecting these excitations is an important step towards understand exotic superconductors, which could help us improve quantum computers and perhaps even pave the way towards room-temperature superconductors.
Professor Jose Lado was awarded early career prize. The award recognizes the talents of exceptional young researchers who are making a significant contribution to their respective field of research. The runner-up prize was awarded to Prof. Lado by Deutsche Physikalische Gesellschaft and Institute of Physics through New Journal of Physics (NJP).
Fazel Tafti (Boston College) will give a seminar "First and second generation Kitaev magnets: The role of topochemistry in quantum magnetism"
Dr. Maia Garcia Vergniory (Donostia International Physics Center/Ikerbasque, Spain) will give a research seminar "Beyond Topological Quantum Chemistry"
By combining ferromagnets and two rotated layers of graphene, researchers open up a new platform for strongly interacting states using graphene’s unique quantum degree of freedom
Prof. Eliška Greplová (TU-Delft Netherlands) will give a research seminar "Learning Algorithms for Control and Characterization of Quantum Matter".
Dr. Timo Hyart (International Research Centre MagTop, Warsaw, Poland) will give a research seminar "Correlated States in Flat-Band Systems".
The colloquium will present novel developments in the field of atomic manipulation with scanning probe techniques and atomically designed quantum matter. This Colloquium series will start on May 4th, and run once a week, preliminary until the end of June.
Dr. Aline Ramires (Max Planck Institute for the Physics of Complex Systems, Dresden, Germany) will give a research seminar "Understanding Complex Superconductors through the Concept of Superconducting Fitness".
The newest theoretical physics professor at Aalto calculates what we need to do to create electronic states that can’t otherwise exist in nature, and how we can harness them for quantum computing