# Research at the KOMKO division

**Our research is 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 spans broader areas of physics. Below, a short introduction is given to the various research activities at the Division of Condensed Matter and Quantum Optics.**

# Eddy Ardonne - Low dimensional and strongly interacting systems

My field of research is condensed matter theory, and I am interested in low dimensional and strongly interacting systems, in particular topological phases of matter. In certain toplogical phases, particles with 'fractionalized quantum numbers' are possible. My research concentrates on the properties of these particles, how one can experimentally detect them, and utilize their properties.

# Ingemar Bengtsson - Mathematical Physics

Mathematical physics can mean many things. I and my students are working on the interplay between geometry and physics, in particular within general relativity theory, and within quantum information theory. Black holes, and the mysterious geometry of quantum state spaces, are very important to us.

# Emil Bergholtz - Interactions and Topology in Quantum Matter

We study quantum many-particle systems for which topology, entanglement and interactions play important roles. These include fractional quantum Hall states, geometrically frustrated magnets, Weyl semimetals and various instances of flat band models. A common feature in these systems is that their low-energy quasiparticles bear little or no resemblance to their electronic constituents.

# Stefano Bonetti - Ultrafast Dynamics in Condensed Matter

Our experimental efforts make use of strong ultrafast laser pulses (from the THz to the visible range) to drive materials out of equilibrium. The response of the systems is probed with femtosecond IR lasers or femtosecond x-ray pulses generated at free electron lasers. Particular focus is on spin dynamics in condensed matter, including time-resolved microscopy of magnetic phenomena using x-rays.

# Mohamed Bourennane - Quantum Information and Quantum Optics

Quantum Information science is a new and interdisciplinary field of research, bringing together quantum physics, computer science, and information technologies. It uses quantum mechanics principles and features, such as superposition principle, entanglement, and non-cloning theorem.

# Hans Hansson - Theory of Quantum Matter

The main focus of my research is on strongly correlated electron systems, and in particlar topological states of matter, the most prominent examples being the fractional Quantum Hall liquids.

# Markus Hennrich - 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. Quantum technologies open many possibilities for applications, as for instance quantum computers that can solve problems intractable by classical computers, quantum-enhanced sensing and metrology, and quantum simulators that can improve our understanding of complex quantum phenomena. These applications are based on the special properties of quantum mechanics, like the exponential scaling of the Hilbert space, or the collective effects in entangled states.

# Vladimir Krasnov - 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.

# Supriya Krishnamurthy - Quantum and Field Theory

My field of research is non-equilibrium statistical physics. Tools and techniques from this field can be used to address not only the properties of systems out-of-equilibrium (such as systems which are driven by temperature gradients), but even of computer networks or of systems of chemical reaction-networks. Most recently, we have investigated some properties of the latter. We have also looked at large deviation properties of noisy driven systems.

# Jonas Larson - Dynamics and exotic states of quantum systems

My research is theoretical and covers a broad range of topics like quantum optics, dynamics of quantum many-body systems, open quantum systems, and quantum phase transitions. More recently I have worked on ultracold atoms in optical lattices and how these systems can be used to simulate quantum magnetism and more exotic states of matter, non-equilibrium quantum phase transitions, chaos and how it relates to thermalization in quantum systems, and open quantum systems.

# Ana Predojevic - 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.

# Andreas Rydh - Quantum materials characterization

Our research is focused on thermodynamic, transport, and structural characterization of materials with novel electronic properties at low temperatures. Particular focus is on superconductivity, magnetism, and other systems with electronic phase transitions, where the effects of a magnetic field and field direction are central. The main experimental technique is nanocalorimetry, sometimes combined with concurrent x-ray diffraction.

# Frank Wilczek - 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. Special areas of focus include (strategies for) detecting axions, manipulating anyons, characterizing time crystals, sculpting long-range forces, and accessing delicate quantum information.

## Condensed Matter and Quantum Optics division

**Head of division**

Eddy Ardonne

Room C5:3025

Tel: +46 (0)8 5537 8596

E-mail: ardonne@fysik.su.se