### Doctoral Research in Physics

VDSP students are the basis of a vibrant community that unites 50 strong research teams in the Faculty of Physics. Our research is driven by the excellence of individuals, which inspire each other.

VDSP students are the driving force behind all research and the essential links between all our research groups. VDSP students have access to the full breath of our physics education and can focus on their own research in many specialized courses, too.

VDSP students are united in the common goal to understand the foundations of physics from high energy, gravitational and mathematical physics to the roots of quantum science. They explore advanced materials and the application of physics to solve challenges of modern society, related to environmental monitoring, energy storage, imaging and measurement tools for materials research or the life sciences or in future of communication and computation technologies.

The following links to the research groups highlight our fields of expertise. The thematic subgroups are connected through joint teaching and meeting programmes, which are described here.

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### Magnetic Simulation

Member of the research group Physics of Functional Materials

Since the rise of high performance computing, numerical simulations are an integral part of material science. For magnetic materials the micromagnetic model has proven to be an excellent tool for the description of static properties of well as the dynamics of the magnetization on the nanoscale. The micromagnetic model is a semiclassical continuum model that accounts for classical fields as well as quantumechanical contributions like exchange coupling and that is able to resolve the inner structure of domain walls. The model is defined in terms of partial differential equations whose analytical solution is only possible for simple edge cases.

### Quantum Nanophysics & Molecular Quantum Optics

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

We are developing universal matter-wave interferometers for quantum experiments with complex and biologically relevant molecules, cluster and nanoparticles. We probe the foundations of quantum physics and are pushing the experimental frontiers to decoherence and the classical world. We build new quantum tools to serve chemistry and molecular analytics and explore a vast range of new particle preparation and cooling techniques across all complexity scales from molecules to dielectric nanoparticles.

### Exploring the Boundaries of Quantum Physics and Gravity in Experiments

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

"How does a quantum object gravitate?”, “How far can we push massive objects into the quantum regime?”, “How well can we measure gravity of microscopic systems?”. Such questions and their implications for the foundations of physics are the driving force behind our research. To address them we are developing quantum measurement and control techniques to investigate and utilize quantum states of motion of massive solid state objects. We are also developing inertial precision sensing techniques to measure the gravitational field of the smallest possible source masses. Our research aims to provide new insights on macroscopic quantum physics, on gravity at small scales and, in the long run, on the phenomenology of the gravity-quantum interface in table-top experiments.

### Taylored Hybrid Structures

Member of the research group Electronic Properties of Materials

The group Tailored Hybrid Structures (THS) works on the production and spectroscopy of filled and substitutionally doped carbon nanotubes.

### Quantum foundations & quantum information theory

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

The goal of our team is to gain insight into quantum foundations and quantum information by exploiting operational and information-theoretic approaches. The team has recently applied them to the field of causality and gravity.

### Mathematical Physics

The Mathematical physics group at the University of Vienna studies theoretical and mathematical questions in quantum field theory, gravity and quantum gravity. The research includes topics like string theory, supergravity and higher-spin gravity, conformal field theory, quantum field theory on non-commutative space-times and many-body quantum physics.

Nils Carqueville's interests include rigorous and elegant approaches to quantum field theory. He employs methods and ideas from algebra, topology and higher category theory to tackle aspects of foundational theoretical physics, their interaction with mathematics, and topological quantum computation.

### Experimental Soft Matter

Member of the research group Computational and Soft Matter Physics

We use light to probe soft matter, ranging from fundamental building blocks, such as colloidal particles and polymers, to commercial products, such as yogurts or softeners; we also study the collective behavior of biological systems, for instance bacteria and epithelial cells. Some of our experiments are performed in collaboration with industry and/or in space, for example on the International Space Station (ISS).

### Gravitational Physics

Piotr Chruściel heads the Gravitational Physics group of the Faculty of Physics. His research has been focused on studies of the global structure of solutions of Einstein equations. This covers questions such as cosmic censorship, asymptotics, as well as many global issues in Lorentzian geometry such as the structure of horizons and the area theorem. He has worked on the general relativistic constraint equations, mass in general relativity, and on classification of black hole space-times. His recent research interests include the understanding of imprints of general relativity on quantum optics.

### Nanomagnetism and Magnonics

The "Nanomagnetism and Magnonics" Research Group is a young and ambitious team that conducts internationally leading research in the field of magnetism. Our main aim is to explore fascinating physical phenomena in the dynamics of magnetic and superconducting systems and to use them for applications.

### Operational quantum information

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

Our research interests follow three principal directions: foundations of quantum mechanics, quantum information theory and practical quantum information.

### Computational Statistical Mechanics

Member of the research group Computational and Soft Matter Physics

Using the computational and theoretical tools of modern statistical mechanics, we study phenomena occurring in complex ordered and disordered systems at the nanoscale. Current research focuses on stochastic thermodynamics, nanoscale materials, interfaces, phase transitions and self-assembly in soft matter. A major research effort of the group consists in developing trajectory-based sampling methods and machine learning approaches for the simulation of molecular systems.

### Magnetism in curvilinear geometries

Member of the research group Nanomagnetism and Magnonics

Magnetism in curvilinear geometries has emerged as a rapidly developing domain of modern magnetism with many exciting theoretical predictions and strong application potential. In the SuperSpinLab, we are investigating geometry- and topology-induced effects in curvilinear magnetic nanostructures. In the focus are objects which have not been realized experimentally so far, such as tori, Möbius strips, and spherical shells. The complex magnetic states in these structures are investigated by a broad range of experimental techniques ranging from magnetometry and magneto-transport measurements to advanced microwave and optical spectroscopy methods.

### Geometric analysis and gravitation

Member of the research group Gravitational physics

I work in the field of Geometric Analysis in the context of Mathematical Physics, more specifically on problems in Mathematical Relativity.

### Holography and Neutron Optics

Member of the research group Physics of Functional Materials

Martin Fally’s research interests include nonlinear optics, neutron optics and interferometry, diffraction & diffraction theories, as well as functional materials.

### Quantum Materials & Quantum Modelling

Member of the research group Computational Materials Physics

The research work is concerned with the theoretical understanding and computational modelling of quantum materials (bulk and surfaces) using first principles methods (primarily VASP). Quantum materials are systems with many interacting degrees of freedom (lattice, spin and electron orbital) that represent a rich platform for the discovery of novel electronic and magnetic phases with fundamental and applicative interest. Specific topics include: Metal-insulator transitions, Polaron physics (electron-phonon interactions), non-collinear spin orderings, topological Dirac/Weyl phases, multiferroism and superconductivity.

### Mathematical Physics

Stefan Fredenhagen’s research deals with mathematical and theoretical questions in quantum field theory, gravity and string theory, with a special focus on two-dimensional conformal field theories and higher-spin extensions of gravity.

### Isotope Physics

Member of the research group Isotope Physics

The Isotope Physics research group operates the particle accelerator "VERA" (Vienna Environmental Research Accelerator), a modern facility for accelerator mass spectrometry (AMS). Research projects focus on the investigation of our world by means of elements occurring in minute traces, using long-lived radioisotopes of both natural and anthropogenic origin. We conduct basic physics experiments as well as a variety of interdisciplinary research programs. Research at VERA contributes to the faculty focus "Physics and Environment".

### Isotope Tracers

Member of the research group Isotope Physics

Our research focuses on the development of sensitive analytical methods based on Accelerator Mass Spectrometry (AMS) to identify characteristic radionuclide signatures to monitor environmental mass transport, e.g. as a response to climate change. This comprises sample preparation methods for different environmental materials as well as employing and extending the advanced AMS instrumentation available at "VERA" (Vienna Environmental Research Accelerator) in order to increase the number of radionuclide tracers accessible by AMS. To answer the question whether a radionuclide is a suitable tracer requires a thorough understanding of its emission sources and its physico-chemical behaviour under the complex environmental conditions. Consequently, our research is strongly interdisciplinary and requires input from various disciplines of environmental science / geology.

### Optical Frequency Combs and their Application

Member of the Faculty Center for Nano Structure Research

The research in the Christian Doppler Laboratory for Mid-IR Spectroscopy and Semiconductor Optics covers all aspects of cavity enhanced frequency comb spectroscopy in the mid-infrared (mid-IR). We strive to extend frequency comb technology further into the mid-IR spectral region and pursue applications with these frequency combs in the field of trace gas detection, precision spectroscopy and molecular fingerprinting.

### Quantum Particles at High and Low Energies

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

Our studies mainly concern the quantum phenomena at high and low energies. Our research spans from very mathematical aspects to experimental ones and, recently, also towards technological realizations.

### Particle Physics

Heavy flavour production at LHC and future Linear Colliders, Jet production at hadron and electron-positron colliders, Determination of quark masses, Radiative corrections in QCD and elektroweak theory; Effective field theories; Theory of unstable particles

### Basic Experimental Physics Training

and University Didactics

The group "Basic Experimental Physics Training and University Didactics" is dedicated to experimental physical basic training and scientific questions on teaching and learning physics.

### Quantum Information and Thermodynamics

Member of the Institute for Quantum Optics and Quantum Information – Vienna

Our group aims to understand the role that information plays in the process of learning about and manipulating our physical environment.

### Quantum Imaging and Biophysics

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

*In any image, the number of detected probe particles is fundamentally limited, either due to finite acquisition times or probe-induced sample damage. In order to optimize the sensitivity of a microscope, the information that can be extracted from each detected probe particle has to be maximized. We achieve this by employing cavity enhancement, quantum enhancement, and wave-front shaping techniques.*

### Dipolar Soft Matter

Member of the research group Computational and Soft Matter Physics

We are using a fine weave of theory and computer simulations to elucidate the properties of dipolar soft matter.

### Stochastic and Quantum Thermodynamics

with Levitated Nanoparticles

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

Cavity-Optomechanics provides a unique approach to Stochastic and Quantum Thermodynamics at the single- and few particle level. The thermodynamic perspective on overdamped mechanical systems has been successfully and much more extensively studied than on well-isolated mechanics. We experimentally investigate such underdamped mechanical systems. Amongst others, this provides a natural first step towards the extension of this approach into the quantum regime. Our focus lies on the application of levitated optomechanics, where all-optical control of the potential landscape seen by a single or few nanoparticles and reservoir engineering of their optical environment are possible. This will provide a general testbed for proof-of-principle implementations to experimentally adress questions at the interface of thermodynamics, information theory and quantum physics, like information or quantum heat engines.

### Nanostructured and novel materials

Member of the research group Physics of Nanostructured Materials

The research focus of the group is to combine surface science and 2D material manufacturing techniques with atomic-resolution electron microscopy to allow creating and studying novel materials and nanostructures with tailored properties.

### Computational Materials Physics

We develop first principles methods for materials sciences. First principles means that no parameters whatsoever are used in the simulations, which is achieved by solving the many body Schrödinger equation. Current research focuses on novel Monte Carlo methods for electrons and the combination of machine learning with first principles methods.

### Superconductivity

Member of the research group Electronic Properties of Materials

Our research focuses on investigations of electronic properties of various novel materials, i.e. physical quantities which are directly related to the response of the charge carriers on electric, magnetic, and electromagnetic fields.

### Soft Matter Theory and Simulation

Member of the research group Computational and Soft Matter Physics

Work in our group focuses on the research area of Theoretical and Computational Physics of Soft Condensed Matter.

### Quantum Control and Quantum Many-Body Physics

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

We are a theory group interested in how to create, control and exploit quantum coherence in the many-body setting. The big questions we address include the interplay of topology, interactions, and disorder, and the control by driving, feedback, and dissipation. We aim at advancing quantum technology and the understanding of non-equilibrium phases of matter.

### Dynamics of Condensed Systems

The group "Dynamics of Condensed Systems" studies the dynamics of atomic diffusion processes, the structure of materials on the nanometer scale and the kinetics of structural changes in those materials. The spectrum of the analyzed materials includes natural composites like bone or wood, metal films, metallic glasses, carbon nano phases and inorganic-organic hybrid systems. We employ both computer simulations like Monte Carlo or Reverse Monte Carlo techniques and experimental methods like X-ray diffraction in our research.

### Low Dimensional Quantum Solids

Member of the research group Electronic Properties of Materials

We dedicate great part of our research to pristine carbon based molecular structures. We aim at understanding which parameters control their electronic structure before one starts to subsequently engineer their properties via different functionalization paths.

### Theory New Physics

Member of the Institute of High Engergy Physics (ÖAW)

Our theory group explores the phenomenology of physics beyond the Standard Model, first and foremost motivated by the dark matter problem. We study axions, weakly interacting massive particles, dark photons, and other particle dark matter candidates. We devise strategies to experimentally and observationally test for their existence and check for their cosmological and astrophysical viability through detailed theoretical calculations.

### Particle Physics

The research group of Massimiliano Procura develops theoretical methods to maximize the discovery potential of both high-energy and high-intensity particle physics experiments.

### Amorphous and Nanostructured Materials

Member of the research group Physics of Nanostructured Materials

Bulk metallic glasses, Mechanical properties of amorphous thin films, Nanocrystalline bulk materials, Nanostructured thin films

### Nanostructured Materials

Member of the research group Dynamics of Condensed Systems

Bulk Nanocrystalline Metals and Alloys, X-ray Profile Analysis, High Entropy Alloys, Functional properties of nanostructured materials, Plasticity of Polymers

### Physics of Functional Materials

Research within the group Physics of Functional Materials focuses on 3D Printing of Magnets, Dynamic Mechanical Analysis, Magnetic Sensors, Magnetic Simulation, Neutron Optics and Diffraction, Nonlinear Optics and Photosensitive Materials and Phase Transitions, Glass Transitions.

### Quantum Information and Quantum Many-Body Physics

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

Quantum Information studies the tasks of information processing and computation using quantum mechanical systems and their non-trivial quantum correlations, termed entanglement. On the other hand, quantum many-body systems exhibit a wealth of unconventional phenomena precisely due to their complex entanglement, which makes them promising candidates for unconventional materials or as a substrate for quantum information processing and computation. We study the interplay of Quantum Information and Quantum Many-Body Physics, combining methods from mathematics, physics, and computer science to obtain a comprehensive understanding of these systems and their usefulness in quantum information processing and computation.

### Dynamics of Condensed Systems

My key research area is the study of the properties of materials, like the dynamics (diffusion and phonons) and kinetics of condensed systems, in particular metallic films, intermetallic alloys, as well as metallic glasses and fast ionic conductors, by scattering and by simulation techniques.

### Covariant Quantum Spaces, Higher Spin, and Gravity

Member of the research group Mathematical Physics.

Harold Steinacker's research interest is the theory of fundamental interactions, and the inclusion of gravity in a consistent quantum framework. The main focus is on an approach known as „Matrix Theory“, which is related to string theory. This provides an independent and well-defined model where space-time and matter are treated on the same footing, and emerge from more fundamental matrix degrees of freedom. The current focus is on the mechanism underlying emergent gravity within that framework.

### Single-atom manipulation

Member of the research group Physics of Nanostructured Materials

The group is focused on understanding the effects of electron and ion irradiation on low-dimensional materials via closely coupled atomically resolved experiments and first principles modeling. Such knowledge enables the implantation of heteroatom impurities into the lattice, reveals their bonding by electron energy loss spectroscopy, and ultimately allows their manipulation with atomic precision using a focused electron beam.

### Physics of Functional Materials

Research within the group Physics of Functional Materials focuses on 3D Printing of Magnets, Dynamic Mechanical Analysis, Magnetic Sensors, Magnetic Simulation, Neutron Optics and Diffraction, Nonlinear Optics and Photosensitive Materials and Phase Transitions, Glass Transitions.

### Computational approaches to phase transitions

Member of the research group Computational and Soft Matter Physics

Most of my research aims at bridging the gap between the traditional phenomenological and mesoscopic vs. the modern atomistic and quantum-mechanical description of phase transitions in condensed matter, a field which constitutes a central area of research in modern theoretical and materials physics. For many decades, phenomenological or semi-quantitative approaches like (i) the Landau theory of phase transitions, which is based on a coarse-grained description of phase transition guided by a rigorous symmetry analysis but numerically determined by fitting a set of expansion coefficients to experimental observables and (ii) the renormalization group theory for critical phenomena have proven to be invaluable tools for our physical understanding of various related phenomena that are often both of theoretical as well as technological importance. Nowadays, however, the arsenal of tools available in modern computational physics allows to significantly refine these concepts. On the one hand, simulations techniques like the Monte Carlo method and molecular dynamics offer to study the statics and dynamics of a given system quantitatively at finite temperature. On the other hand, using quantum mechanical computations based on e.g. modern density functional theory (DFT) we are able to access realistic microscopic energies and forces with high accuracy. For instance, we have recently extended classical Landau theory to high pressure structural phase transition by incorporating information from DFT. In cooperation with faculty member Wilfried Schranz we study the possible emergence of nonzero polarization in domain walls between non-polar domains with a recently developed layer group symmetry analysis technique. Presently we aim at developing computational approaches involving the machine-learning techniques developed in the Dellago group, which will be combined with Monte Carlo and DFT to simulate this phenomenon on the atomistic level.

### Computational Materials Discovery

Member of the research group Computational Materials Physics

We are an interdisciplinary team developing theoretical and computational methods for physics based studies of chemical and material compound space. Our lab was first established in 2013 in Basel, Switzerland, and moved to Vienna in October of 2020. Due to the interdisciplinary nature of our work, we rely heavily on quantum mechanics, statistical mechanics, physical chemistry, materials sciences, applied mathematics, and computer sciences.

### Phase transformation in Nanomaterials

Member of the research group Physics of Nanostructured Materials

Reversible shape changes of ferroelastic materials showing martensitic phase transformations can be controlled by temperature, stress or magnetic fields. Grain size at a nanoscale can strongly impact the martensitic phase transformation and therefore the shape memory effect and superelasticity. Nanocrystalline and ultrafine grained shape memory materials including NiTi alloys, low-hysteresis NiTiPd alloys, and ferromagnetic high-temperature NiMnGa alloys are processed by methods SPD. The lattice structures of the martensitic phases, self-accommodated martensitic domains, transformation temperatures, as well as the enthalpy and entropy changes upon transformation are studied by systematic experiments. These results are analysed using thermodynamic models considering the total Gibbs free energy of ferroelastic domains confined to small grains.

### CMS Physics Analysis

Member of the Institute of High Energy Physics

At HEPHY in Vienna I have started an analysis group that searches for signs of supersymmetry at CMS. In the last few years, though, I have focussed on the interpretation of the search results: given a positive or a null result, what are its implications? What do the data really tell us about supersymmetry, or other theories, and the question of naturalness? To this end I founded a small collaboration, and together we developed "SModelS", a software framework that allows us to confront an arbitrary theoretical model with LHC results. It is my ultimate vision that we can learn the fundamental physical laws beyond the Standard Model in an unsupervised fashion, employing modern machine learning techniques.

### Quantum Information Science and

Quantum Computation

Member of the research group Quantum Optics, Quantum Nanophysics and Quantum Information

Our research combines the development of scalable photonic quantum technology for quantum computing and other quantum information applications with the investigation of fundamental quantum science questions. The main activities reach from quantum control of single photons using solid-state photon sources, integrated waveguide technology, tailored nonlinear media and detectors based on superconductor technology to interferometric precision measurements of weak gravitational forces.

### Aerosol physics and environmental physics

A particular strength of the group is in the development, adaptation and testing of measurement techniques, with a long track record of ground-breaking designs and technologies. Inter-disciplinary research investigates zones in exoplanetary systems supporting life based on solvents other than water. Current research is continually integrated into lectures and lab classes on aerosol science, environmental science and global change.

### Hyperfine Structure of Antihydrogen

Member of the Stefan Meyer Institute for Subatomic Physics

The goal of the project is to study the hyperfine structure of antihydrogen, the simplest antimatter atom, and thus search for a violation of the charge-parity-time (CPT) symmetry of Nature. In parallel activities within the AEgIS collaboration at CERN-AD were pursued to evaluate a different approach of creating a slow beam of antihydrogen atoms needed for the measurement.

### Aerosol Nanoparticle Formation

Member of the research group Aerosol Physics and Environmental Physics

Aerosol nanoparticle formation has been identified as a significant source of ambient aerosol that may impact cloud properties and is considered a health threat. Our research aims at resolving the initial steps in the transition of (trace) vapors to the condensed phase in nanoparticles. Such phase transition processes constitute a vital link between molecular scale interactions and macroscopically relevant outcome.