Department of Applied Physics

Correlated Quantum Materials (CQM)

Theoretical condensed matter physics, focusing on emergent properties of quantum materials.
HF TTG

 

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:

Heavy fermions TaS2
Artificial heavy fermions in a van der Waals heterostructure, Nature 599, 582–586 (2021)

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.

 

Cascade
Critical cascade in quasiperiodic chains, Nature Physics 16, 832–836 (2020)

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.

 

TSC
Two-dimensional topological superconductivity with antiferromagnetic insulators, Phys. Rev. Lett. 121, 037002 (2018)

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 to probe the non-uniform superfluid density in superconducting twisted graphene trilayers.

Hybrid tensor-network neural-network algorithm
Neural-network enhanced hybrid quantum many-body dynamical distributions, Phys. Rev. Research 3, 033102 (2021)

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)
- 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)

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)
- Vilja Kaskela: Research assistant
- Senna Luntama: Research assistant (co-supervised with Prof. Päivi Törmä)

Research Group Members

Jose Lado

Jose Lado

Assistant Professor
[email protected]
+358503133730
Guangze Chen

Guangze Chen

Doctoral Candidate
[email protected]
Maryam Khosravian

Maryam Khosravian

Doctoral Candidate
[email protected]
Rouven Koch

Rouven Koch

Doctoral Candidate
[email protected]
Pascal Vecsei

Pascal Vecsei

Doctoral Candidate
[email protected]
Marcel Niedermeier

Marcel Niedermeier

Doctoral Candidate
[email protected]
Timo Hyart

Timo Hyart

Research Fellow
[email protected]
Faluke Aikebaier

Faluke Aikebaier

Visiting Postdoctoral researcher
[email protected]
Adolfo Fumega

Adolfo Fumega

Postdoctoral researcher
[email protected]

Recent Events & News

Jose Lado, photo: Evelin Kask

Early career award granted to Professor Jose Lado

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).

News
An artistic rendition of quantum entanglement. Image: Heikka Valja

A new artificial material mimics quantum entangled rare earth compounds

By combining two-dimensional materials, researchers create a macroscopic quantum entangled state emulating rare earth compounds

News
Scehmatic of a heavy fermion on graphene

Unlocking radiation-free quantum technology with graphene

A new paper has shown it is possible to make heavy fermions in subtly modified graphene, which is much cheaper and safer

News
photo of Fazel Tafti

Department of Applied Physics Research Seminar: Fazel Tafti

Fazel Tafti (Boston College) will give a seminar "First and second generation Kitaev magnets: The role of topochemistry in quantum magnetism"

– Events
A cartoon showing a graphene lattice with a strip of blue in the middle representing the topological superconductor

A path to graphene topological qubits

Researchers demonstrate that magnetism and superconductivity can coexist in graphene, opening a pathway towards graphene-based topological qubits

News
web advert showing graphic about a superconductor's transmission properties

Department of Applied Physics Research Seminar: Mohamed Oudah

Dr. Mohamed Oudah (UBC, Can) will give a research seminar "Unusual Sn State in the Superconducting Disordered Selenide Ag1-xSn1+xSe2"

– Events
A photo of Maia Vergniory smiling with a scientific graphic showing a periodic table

Department of Applied Physics Research Seminar: Maia G. Vergniory

Dr. Maia Garcia Vergniory (Donostia International Physics Center/Ikerbasque, Spain) will give a research seminar "Beyond Topological Quantum Chemistry"

– Events
Twisted graphene sheets give rise to electrons with exotic properties

A magnetic twist to graphene

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

News
Profile

AQP Seminar: A NEAT Quantum Error Decoder

Aalto Quantum Physics Seminar (Zoom). Speaker: Prof. Evert van Nieuwenburg (Niels Bohr International Academy, Denmark)

– Events
A graphic representing learning algorithms for quantum matter

Department of Applied Physics Research Seminar: Eliška Greplová

Prof. Eliška Greplová (TU-Delft Netherlands) will give a research seminar "Learning Algorithms for Control and Characterization of Quantum Matter".

– Events
Seminar advert Timo Hyart

Department of Applied Physics Research Seminar: Dr. Timo Hyart

Dr. Timo Hyart (International Research Centre MagTop, Warsaw, Poland) will give a research seminar "Correlated States in Flat-Band Systems".

– Events
Magnetic materials

A road to frustration

Aalto University theorist part of a team that opens up a new route to design exotic frustrated
quantum magnets.

News
Scanning tunneling microscope tip confining electrons in graphene

Stopping the unstoppable with atomic bricks

Aalto University theorist part of a team that developed a method for trapping elusive electrons

News
Schematic of a wave passing through a quasiperiodic structure

A critical cascade

New Nature Physics paper shows how quantum particles approach an elusive critical regime in a quasiperiodic structure.

News
Collage of the academy of Finland Fellow

Meet our newest Academy of Finland Fellows

Our researchers who have been awarded Academy of Finland Fellowships tell us about what their projects will investigate

News
Image of Atomic scale quantum materials colloquium

Atomic scale quantum materials colloquium: new online colloquium series (external link)

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.

graphic describing superconductivity fitness concepts

Department of Applied Physics Research Seminar: Dr. Aline Ramires

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".

– Events
physics research seminar advert

Physics Research Seminar

Tobias Wolf (ETH Zürich, Switzerland) will give the seminar "Metamaterials from Twisted Honeycomb Lattices" about his research.
Hosted by Prof. Jose Lado.

– Events
Pizza_slice

PHYS brown bag seminar: Topological and correlated quantum matter in twisted graphene multilayers

Join us for science and pizza in the Nanotalo lobby!

– Events
Professor Lado in the physics department coffee room

How to create things that don’t exist

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

News

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