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Research subject Condensed Matter and Quantum Optics

The research of Condensed Matter and Quantum Optics is both experimental and theoretical.

The research focuses on the fundamental aspects of quantum phenomena in light and matter, and has several potential applications in quantum information technology, quantum electronics and nanotechnology. Theoretical work also span broader areas of physics.

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Physics
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Researchers

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Research groups

Experimental Condensed Matter Physics

Research in the group is focused at the study of mesoscopic phenomena in condensed matter physics. Our research areas span over superconductivity (with emphasis on high temperature superconductors), low temperature physics, quantum electronics and spintronics, and nanotechnology.

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Quantum Frontiers

The Wilczek group explores several frontiers of quantum theory where new or hitherto impractical theoretical concepts are making contact with experimenters’ increasing ability to explore and control the quantum world.

Quantum Frontiers
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Quantum photonics

Semiconductor devices and non-linear processes can generate a wide spectrum of quantum states of light that can be employed in tasks of communication, simulation, and sensing. We use best tools and methods available to modern science to generate quantum light, harness its unique properties, and bring it closer to real-world application.

Quantum Photonics
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Trapped Ion Quantum Technologies

Due to a significant technical progress and precise engineering, we are nowadays able to manipulate individual quantum systems, like single atoms, with a precision that has been unthinkable a few decades ago.

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Research projects

Dynamics of open and closed quantum systems

While entanglement is the primary threat of quantum mechanics, it is also the reason why simulating quantum systems by classical means is challenging. We explore complex quantum systems and explore methods for their simulation.

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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.

Research
Locality vs. topology in quantum matter

This project brings together several frontiers of basic science - from materials science and quantum optics to the theory of topological phases and modern mathematics - with a potential to provide a basis of future technology.

Research
Many-body effects in Weyl Semimetals

Topological semimetals are a class of materials in which electrons obtain exotic propoerties that are not found in elementary particles in nature. We examine Coulomb interaction in these.

Research
Quantitative analysis of non-equilibrium systems

Non equilibrium systems abound in nature on all scales but general principles that guide their working are not known. This project concerns investigating an aspect that all non-equilibrium systems have in common- entropy generation.

cartoon summarizing the most important features of this project
Quantum Materials with Anisotropic Heavy Fermions

Quantum materials are materials with strong electronic correlation and emergent orders. In this research project we will experimentally study quantum materials in systems with strongly anisotropic properties.

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Sculptured Topological Heterostructures

In this theoretical project, we intend to investigate what happens when we assemble exotic topological components. More specifically, we want to investigate four types of "sculptured topological heterostructures" as briefly described below.

Research
Three-dimensional topologically ordered phases

We study topologically ordered systems. One of their characterizing features is quantum number fractionalization, e.g. quasiparticle excitations can carry charge that is a fraction of the elementary electron charge.

Research
Topological phases and their transitions

Topological phases of matter are amongst the most interesting phases that are being studied, both theoretically as well as in experiments. In this project, we focus on the various types of phase transitions that topological phases can undergo.

Research
Ultrafast magnetism

An often forgotten energy consumer is the internet. Data centres, where information is stored in the form of magnetic bits, waste most of their energy as heat. Improve the control over magnetic information is crucial for our society is to prosper.

ERC Magnetic Speed Limit Logo - ERC Logo för magnetisk hastighetsbegränsning

Courses and programmes

At the Department of Physics at Stockholm University, we offer high-quality education with a strong connection to frontier research. We promise exciting studies in tight student groups and with active researchers as your teachers.

Courses and programmes

Doctoral studies

At Fysikum there are four postgraduate subjects: physics, theoretical physics, chemical physics and medical radiation physics.

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News

Professor Emil Johansson Bergholtz outside AlbaNova. Photo: Gunilla Häggström
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.

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Kvinnliga fysiker på Kvinnodagen 2024
Department of Physics

International Women's Day 2024: Women in physics

March 8 is International Women's Day and today we want to highlight women in physics. There are many examples including Marie Curie, Maria Goeppert Mayer and Lise Meitner to Fabiola Gianotti and Lene Hau. We also mention some of the female professors of physics who belong to the Fysikum.

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David Marsh, assistant professor, Fysikum
Department of Physics

David Marsh is Vice Director of EuCAPT

EuCAPT is a European consortium for astroparticle theory. It aims to bring together European researchers in theoretical astroparticle physics and cosmology. In early February, David Marsh took over as Vice Director of the consortium. At Fysikum he is a researcher in astroparticle physics and teaches the course Quantum Phenomena and Radiation Physics.

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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.

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AT_bs_prversionb
Department of Physics

Single-Shot Measurements of Phonon Number States Using the Autler-Townes Effect

Efficient and reliable detection of motional states is an essential component of many ion-trap experiments. In this recent work a new technique for measuring both Fock and thermal states, based on the Autler-Townes splitting, is demonstrated. The experimental work has been carried out in the group of Markus Hennrich at Fysikum, and was performed in collaboration with the groups of Celso Villas-Boas and Romain Bachelard in São Carlos, Brazil.

Nobel Prize in Chemistry
Department of Physics

The Nobel Prize in Chemistry 2023 - Quantum dots

Moungi G. Bawendi, Louis E. Brus and Alexei I. Ekimov were awarded the Nobel Prize in Chemistry 2023 for the discovery and development of quantum dots. These tiny quantum systems have unique properties and many applications: they emit light used in television screens and LED lamps, they catalyse chemical reactions, and their emission marks the borders of tumor tissue for a surgeon. Ana Predojević, is associate professor at Fysikum: "We use the best tools and methods available to modern science to generate quantum light, harness its unique properties, and bring it closer to real-world application."

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Flätskyddade topologiska bandstrukturer med oparade exceptionella punkter
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.

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Non-Hermitian Systems
Department of Physics

Quantum metric unveils defect freezing in non-Hermitian systems

The fundamental postulates of quantum mechanics rest upon the fact that the Hamiltonian, which quantifies the energy of the system, is given by a Hermitian operator. This means that the complex conjugate and transpose of the Hamiltonian should be equal to itself. Almost a century after the formulation of quantum mechanics, researchers are now trying to break free from this constraint — non-Hermitian Hamiltonians, which do not satisfy the aforementioned property, are now a new frontier of exploration in both theoretical and experimental physics. Paolo Molignini is part of the project and is a Postdoctor in Condensed Matter and Quantum Optics at Fysikum.

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Frank Wilzcek, Nobel Laureate and professor at Fysikum. Photo: Gunilla Häggström
Department of Physics

Frank's curiosity has earned him the Nobel Prize and several fruitful collaborations

Professor Frank Wilczek's was interested in mathematics and big numbers even as a child. His father was an electrical technician who fixed radios and tvs when they were broken. Frank was inspired and liked to take apart and put together things to see how they worked. This was the beginning of a fantastic career in Physics. In 2004, Wilczek received the highest honor in science — the Nobel Prize in Physics — for his discovery of asymptotic freedom and the development of the theory of quantum chromodynamics (QCD). Since 2016 he has been working at the Department of Physics.

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Scanning electron image of a small vortex-based memory cell.
Department of Physics

Word and bit line operation of a 1x1 μm2 superconducting vortex-based memory

The third industrial “digital” revolution is on the way. The volume of digital information, the amount of large computation facilities and the related energy consumption are growing in an explosive manner. The notorious “memory wall” problem reveals ineffectiveness of the standard processor-centered computation for processing of big data volumes and actuates the necessity of both hardware and software development for new types of in-memory computation. Simultaneously, silicon-based electronics is approaching its limits. The large resistivity of nano-scale semiconductor transistors and interconnections impedes operation speed and causes severe heat management problems. Sustainability of the present digitalization trend requires radical innovative solutions.

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Gruppfoto från workshopen om att utforska simuleringar av gravitation och kvantgravitation
Department of Physics

Workshop about exploring simulations of gravity and quantum gravity

In July Fysikum hosted a workshop in Stockholm, jointly organized by Igor Pikovski from Fysikum and Rivka Bekenstein from the Hebrew University of Jerusalem. Its focus was the study of quantum gravity in the lab. 20 participants spent 3 days at Näsby Slott to discuss quantum simulations and quantum aspects of gravity.

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Professor Mohamed Bourenanne and PhD student Thomas Daugey
Department of Physics

New quantum communication infrastructure

Mohamed Bourenanne is part of the National Quantum Communication Infrastructure in Sweden (NQCIS) project, which received SEK 30 million from Vinnova and is coordinated by KTH. His research group works in the field of quantum communication and their laboratory is located at AlbaNova. - All eavesdropping attempts can be revealed thanks to the basic theories of quantum mechanics, thus increasing information security.

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KS18 and its graph of compatibility
Department of Physics

Quantum mechanics predicts effects that are counter-intuitive

Quantum mechanics predicts effects that are counter-intuitive and impossible to reconcile with our daily experience. One of the most intriguing examples of these predictions is that a pair of particles can be entangled. When two particles are entangled we cannot describe the properties of one of them without referring to the other, they behave as a single entity.

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The Future is Quantum
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.

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Department of Physics

Frank Wilczek on the 2022 Physics prize

Frank Wilczek is professor of theoretical physics at MIT and The Department of Physics at Stockholm university and a Nobel laureate. He held the Nobel prize in physics in 2004. Hear him comment on the Physics Prize of 2022, and giving advice to this year´s laureates arriving in Stockholm in December.

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Departments and centres

Research in the subject is mainly carried out at Fysikum in the division of Condensed Matter and Quantum Optics.

Department of Physics