Projects / Programmes
Theory of the condensed matter and statistical physics
January 1, 2015
- December 31, 2021
| Code |
Science |
Field |
Subfield |
| 1.02.00 |
Natural sciences and mathematics |
Physics |
|
| 1.07.00 |
Natural sciences and mathematics |
Computer intensive methods and applications |
|
| Code |
Science |
Field |
| P002 |
Natural sciences and mathematics |
Physics |
| Code |
Science |
Field |
| 1.03 |
Natural Sciences |
Physical sciences |
Correlated Electron Systems, Superconductivity, Nonequilibrium dynamics, Exact solutions, Integrability, Transport, Heavy fermions, Dynamical mean-field theory, Impurity physics, Nanophysics, Quantum bits, Self-assembled nanonetworks, Information diffusion.
Researchers (54)
Organisations (2)
Abstract
We will study equilibrium properties and non-equilibrium dynamics of many body quantum systems. An important class of such systems are compounds with strongly correlated electrons revealing a rich variety of ordered phases at low temperatures. In the framework of microscopic models of correlated electrons we will investigate their equilibrium as well as non-equilibrium properties. In equilibrium we will determine the influence of interaction on their transport properties, transitions between different ordered states and their thermodynamic properties. Away from the equilibrium we will investigate the response of the system to short-time external perturbation. We will extend the linear response theory to study optical conductivity and spectral functions under nonequilibrium conditions and investigate mechanisms for thermalization in closed quantum systems.
We shall also consider fluctuation properties of many body quantum systems out of equilibrium. For simple model systems we will try to find exact solutions -- we have already developed some rather successful methods in this respect. An important quantity are also (local or pseudolocal) constants of motions that can in turn help us to understand quantum transport. We will also systematically investigate stability of conserved operators to generic types of integrability breaking perturbations. Findings from model systems will be then used to design and study quantum systems with interesting transport properties, e.g., large cross-transport coefficients (e.g. thermopower).
We will study heavy-fermion compounds. These materials contain partially filled d- and f-shell orbitals, which have very complex phase diagrams with different magnetic, charge/orbital ordered and superconducting phases due to strong interactions. We aim to unravel the phase diagram of the Kondo lattice model within the dynamical mean-field theory and its non-local extensions. We will investigate topological insulators and superconductors, focusing on their edge states (chiral/helical electrons, Majorana fermions).
In the field of nanophysics we will continue our research in the area of processing of quantum information and manipulation of quantum qubits. We will explore the relevance and influence of the environment such as, e.g. fluctuations of local electric field due to moving quantum dot, on the decoherence and relaxation of a qubit, a subject of great relevance for the emerging tecnologies for next generatin computres.
Research in statistical physics of complex systems and networks we plan to continue using graph theory and advanced numerical methods. Within the concept of nanonetworks, we will study structural and dynamical features of self-assembled nano-materials and molecular interactions at single-molecular level. Furthermore, we will expand the investigation of collective dynamics and agent-based modeling of social interactions, which we have recently conducted within FP7 project.
Significance for science
The proposed research program encompasses many research fields, covering a number of topics in the theory of statistical physics and condensed matter physics, which are at the forefront of research activities worldwide and have great application potential for new technologies. The research milestones set by our group have a firm basis in the achievements accomplished so far and internationally recognized for its quality. In the past six-year period we have published over 190 scientific papers, 30 were published in the eminent magazine Physical Review Letters while most of published articles, 156, belong to the highest A1 category. Members of the research program have won distinguished awards for their scientific achievements. J. Bonča was in 2012 awarded the Zois award, which is the highest state award for outstanding scientific achievements, T. Prosen has in 2009 won the Friedrich Wilhelm Bessel award that is given by the Humboldt foundation. J. Mravlje and L. Vidmar, were awarded the Golden emblem of J. Stefan for their PhD thesis. Below we briefly summarize and highlight the main subjects of our proposal.
In the theory of strongly correlated electrons we mainly address issues related to models related to the phenomenon of high-Tc superconductivity, to frustrated spin systems and to their anomalous thermal and transport properties. The ever growing list of new materials, while tantalizing for materials' physical properties, offers unforeseen opportunities for technological applications in many areas of human activity (e.g., high transition temperature to superconducting state, anomalously large thermal conduction of certain low-dimensional insulating spin systems etc.). The theoretical investigations in the field of nanosystems are of great importance for the understanding and development of new nano-devices and their potential application in e.g., medicine, public administration and affairs, households, etc.. Equally important is the the quantum computing and informatics, where a thorough understanding of decoherence effects is instrumental to an effective implementation of quantum computation algorithms and communication protocols. This subject is of great importance for the field of cryptography. Another topic originates from the more general field of statistical mechanics and is devoted to the study of the complex dynamical systems and networks, a topic with potentially large impact in a vast area of socio-economic infrastructure. We will developt novel numerical methods for quantum systems and in this connection also maintain state of the art computing capabilities. We have developed a new method to study many body systems at finite temperatures and a highly efficient method to study a doped charge carrier in a spin background. We have as well developed a very efficient mehtod of Numerical Renormalization Group that si freely available on the Web and used by many researchers worldwide.
Significance for the country
We are confident that our community as a whole benefits from our research efforts – which we strive to keep on an as high level as possible – for several reasons. While keeping pace with research at the forefront of the many topics in statistical physics and physics of the solid state, we are able to competitively interact with research groups worldwide, thus providing direct means for the enrichment of national scientific and cultural heritage. In the past research period we have organized 5 international conferences ( two on Yalta, Ukraine and the rest in Slovenia) while our researchers have presented invited talks on over 100 international conferences. Organization of international conferences, invited plenary talks on well recognised international conferences, citations of our work in review articles, publication of our research results in renowned journals, membership in international boards, joint EU projects and bilateral projects worldwide, all these contribute to the recognition of Slovenia as a modern European country with a well developed scientific and technological basis. Our achievements contribute also to our self awareness and confidence as a small nation amid the global community. We would like to underscore two more spin-off segments of our research activity for the nationwide benefit: the education of students and young researchers through the constant involvement in teaching processes at the Universities of Ljubljana and at the J. Stefan International Postgraduate School. Another segment is maintenance of high-level research conditions, being a sine-qua-non for achieving a high added value to our domestic “products”, either intellectual or material, in the world of global economy. Our young researchers already during their graduate studies publish in eminent international magasines such as Physical Review Letters while the number of authors on such publications is typically between 2 and 4. As an example, L. Vidmar has published 6 publications in the above mentioned magasine during his graduate studies and was for his achievements awarded the Golden emblem of Jožef Stefan.
Most important scientific results
Annual report
2015,
interim report
Most important socioeconomically and culturally relevant results
Annual report
2015,
interim report
