Department of Applied Physics

Correlated Quantum Materials (CQM)

Theoretical condensed matter physics, focusing on quantum materials engineering.
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 van der Waals materials, including graphene, two-dimensional superconductors, magnets and multiferroics. In our group, we aim to provide theoretical routes to engineer exotic states of matter in twisted van der Waals systems, including graphene, 2D superconductors, ferromagnets and multiferroics. 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 developing new methodologies to treat quantum many-body fractional matter using both neural-network, tensor-network and quantum-circuit algorithms. Besides our theoretical research lines, we often work in collaboration with experimental groups studying quantum materials in general, and van der Waals materials in particular.

 

Current main research lines:

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

Engineering and controlling quantum matter 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, we recently showed: 
Controlling artificial gauge fields electrically in twisted graphene multilayers
Designing frustrated valley magnets in twisted graphene multilayers 
Generating electrically controllable correlated states in twisted graphene multilayers
- Engineering artificial heavy-fermion correlated states in twisted graphene multilayers
- Revealing the mechanism leading to multiferroic order in a van der Waals monolayer 
In collaboration with experimental groups, we recently experimentally demonstrated:
Realizing an artificial many-body heavy-fermion state in van der Waals multilayers 
Probing magnetic excitations in van der Waals magnets
- Designing magnetically frustrated van der Waals magnets with spin-orbit coupling engineering
Probing crystal field effects in twisted graphene multilayers.

Current main research lines:
- Tunable correlated quantum matter in twisted van der Waals materials
- Van der Waals multiferroics
- Heavy-fermion Kondo quantum matter in van der Waals materials

 

NCAR
Noncontact Andreev Reflection as a Direct Probe of Superconductivity on the Atomic Scale, Nano Lett. 2022, 22, 10, 4042–4048 (2022)

Designing and detecting emergent excitations in quantum materials
The interplay of strong electronic interactions, quasiperiodicity and dissipation represents one of the most exciting lines in quantum materials, 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:
Engineering topological excitations by exploiting quasiperiodic many-body states
Designing topological modes by exploiting Coulomb engineered correlations 
Designing solitonic excitations between quantum disordered magnets and superconductors
- Engineering topological modes in non-Hermitian interacting systems 
In collaboration with experimental groups, we experimentally showed:
Generating and probing criticality in quasiperiodic states 
- Promoting topological superconducting excitations with moire patterns
- Detecting electronic quantum entanglement at the atomic scale

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.

Current main research lines:
- Non-Hermitian interacting many-body topology
- Quasiperiodic-driven many-body topology
- Interaction-driven topological quantum matter

GAN
Designing quantum many-body matter with conditional generative adversarial networks, Phys. Rev. Research 4, 033223 (2022)

Quantum algorithms and machine learning for quantum materials design
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 tensor-network, neural-network and quantum circuit algorithms. In this direction, recently we demonstrated:

Powering-up many-body methodologies with neural-network algorithms
Detecting topological quantum matter with neural-network algorithms
Computing dynamical topological excitations in many-body systems using kernel polynomial tensor-network methods
- Exploiting tensor-network algorithms to predict quantum many-body criticality
- Exploiting generative adversarial machine learning for dynamical quantum matter and Hamiltonian learning 

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 main research lines:
- Generative-adversarial machine learning for many-body quantum materials
- Tensor-network methods for non-Hermitian dynamical quantum many-body matter
- Quantum-circuit tensor-network algorithms for quantum matter
- Neural-network and tensor-network methods for quantum criticality

Current group members:
- Jose Lado: Assistant professor
- Guangze Chen: Doctoral Researcher
- Maryam Khosravian: Doctoral Researcher (co-supervised with Prof. Peter Liljeroth)
- Rouven Koch: Doctoral Researcher
- Pascal Vecsei: Doctoral Researcher (co-supervised with Prof. Christian Flindt)
- Marcel Niedermeier: Doctoral Researcher (co-supervised with Prof. Christian Flindt)
- Elizabeth Pereira: Doctoral Researcher (co-supervised with Dr. Andrea Blanco-Redondo)
- Vilja Kaskela: MSc Student (co-supervised with Dr. Adolfo Fumega)
- Faluke Aikebaier: Magnus Ehrnrooth Postdoctoral Researcher (co-supervised with Prof. Teemu Ojanen)
- Adolfo Fumega: Academy of Finland Postdoctoral Researcher (co-supervised with Prof. Peter Liljeroth)

Former group members
- Netta Karjalainen: Research Assistant (co-supervised with Prof. Theo Kurten)
- Zina Lippo: Research Assistant
- Marc Nairn: Research Assistant (co-supervised with Prof. Christian Flindt)
- Timo Hyart: Research Fellow
- 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

 Jose Lado

Jose Lado

Assistant Professor
 Guangze Chen

Guangze Chen

Doctoral Researcher
 Maryam Khosravian

Maryam Khosravian

Doctoral Researcher
 Rouven Koch

Rouven Koch

Doctoral Researcher
 Pascal Vecsei

Pascal Vecsei

Doctoral Researcher
 Marcel Niedermeier

Marcel Niedermeier

Doctoral Researcher
 Elizabeth Pereira

Elizabeth Pereira

Doctoral Researcher
 Vilja Kaskela

Vilja Kaskela

MSc Student
 Faluke Aikebaier

Faluke Aikebaier

Magnus Ehrnrooth Postdoctoral Researcher
 Adolfo Fumega

Adolfo Fumega

Academy of Finland Postdoctoral Researcher

Recent Events & News

Illustration of controlling internal states of molecules with electric fields.

Controlling quantum states in individual molecules with two-dimensional ferroelectrics

Researchers demonstrated how to control the quantum states of individual molecules with an electrically controllable substrate.

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Depiction of quantum materials

Designing quantum materials with quantum computers

The Jane and Aatos Erkko Foundation awards a proof-of-concept grant for the design of quantum materials with quantum computers.

News
Fernando de Juan

AQP Seminar: Electronic instabilities of metallic dichalcogenides: Unconventional superconductivity and Kondo magnetism

Aalto Quantum Physics Seminars (Hybrid). Speaker: Dr. Fernando de Juan (Donostia International Physics Center, Spain)

Events
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AQP Seminar: Fractional Chern Insulators in Magic Angle Twisted Bilayer Graphene

Aalto Quantum Physics Seminars (Hybrid). Speaker: Dr. Cécile Repellin (CNRS, Laboratoire de Physique et Modélisation des Milieux Condensés, France)

Events
Professor Jose Lado, facing the camera, sitting on wooden steps.

An atomic-scale window into superconductivity paves the way for new quantum materials

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.

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Raquel Queiroz

Department of Applied Physics Research Seminar: Raquel Queiroz

Impurity states and disorder in crystalline symmetry protected topology

Events
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

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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

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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

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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

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Profile

AQP Seminar: A NEAT Quantum Error Decoder

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

Events
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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
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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.

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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

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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.

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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
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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.

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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

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