### Research topics

 Magnet-superconductor hybrid systems   Nano-scale heterogeneous systems consisting of magnetic and superconducting parts, such as quantum dots embedded in Josephson junctions, nanowires coated with a superconducting layer, or magnetic molecules adsorbed on superconductor surfaces, host long-lived excitations inside the gap (Yu-Shiba-Rusinov states, Andreev bound states). These excitations can be exploited in various quantum devices for quantum information storage and processing. We explore the basic physics of the sub-gap states, often in collaboration with leading experimental groups, and we develop novel theoretical tools required to tackle these strongly correlated problems.   dr. Rok Žitko Luka Pavešić   Back to the top Phase diagrams of a quantum dot coupled to a superconducting island for different ratios of charging energy to superconducting gap, as a function of gate voltages applied to the dot and the island.

 Electronic correlations in multi-orbital materials   Many materials are multi-orbital, that is, more than one active orbital is important. The Hund's rule coupling that splits atomic multiplet splittings has been found to importantly affect the strength of electronic correlations in a way that depends on the filling of the orbitals. Hund's rule coupling can cause strong correlations far from a Mott insulating state. Materials in which Hund's rule coupling is playing the key role, such as ruthenates and iron pnictides, are known as Hund's metals. With dynamical mean-field theory calculations we are investigating properties of this family of compounds.   dr. Denis Golež dr. Jernej Mravlje dr. Rok Žitko   Back to the top

 Electronic and spin-transport in bad metals   Many metals in which electronic correlations are important are bad, that is, their resisistivity exceeds the Mott-Ioffe-Regel value which corresponds to the resistivity a material has when the scattering events are so frequent that the electron mean-free path is equivalent to the lattice spacing. Using finite-temperature Lanzczos method, dynamical mean-field theory, and its cluster generalizations we are exploring the mechanism of electronic and spin transport in this regime.   Martin Ulaga dr. Jure Kokalj dr. Rok Žitko dr. Jernej Mravlje dr. Janez Bonča dr. Peter Prelovšek   Back to the top

 Relaxaton dynamic of complex quantum systems   Relaxation of a photo-doped charge carrier in the spin background Relaxation dynamics of the Holstein polaron  Driven strongly correlated electron and electron-phonon coupled  systems  far from the equilibrium    dr. Janez Bonča dr. Denis Golež dr. Lev Vidmar dr. Peter Prelovšek   Back to the top From Phys. Rev. Lett. 106, 196401 (2011).

 Finite - T properties of lattice polaron systems   Spectral properties of a charge coupled to various bosonic degrees of freedom Thermalization of a highly excited charge carrier via lattice degrees of freedom   dr. Janez Bonča dr. Lev Vidmar   Back to the top Holstein polaron spectral function. From Phys. Rev. B 100, 094307 (2019).

 Static and dynamic properties of disordered complex quantum systems   Unusual properties of driven disordered quantum systems  Dynamics of disordered systems coupled to various bosonic baths   dr. Janez Bonča   Back to the top From Phys. Rev. Lett. 119, 246601 (2017).

 Theory of quantum spin liquids   Quantum spin liquids are spin systems on frustrated lattices, which do not exhibit any magnetic long range order at low temperatures. Their existence and properties offer several challenges to theoreticians, also in connection with recent experiments on several classes of real spin-liquid materials. Our studies focus on relevant basic spin models, calculating numerically their finite-temperature thermodynamic and dynamical properties, also in close collaboration with experimental group at IJS.   dr. P. Prelovšek dr. J. Kokalj   Back to the top
 Collective phenomena in complex systems and networks   Current research of complex systems focuses on their complex geometry, which may have evolved through evolutionary optimization that allows for new functional properties. Higher organized complexes are recognized as aggregates of simplexes (triangles, tetrahedra, and higher cliques) and can be described by algebraic topology methods. Beyond pairwise interactions, these simplicial complexes enable higher-order interactions based on geometry, which may be crucial for the emergence of new dynamical phenomena on networks. By combining the methods of Statistical physics with Graph theory and Algebraic topology of graphs we investigate: Structure of simplicial complexes in brain networks based on the neuroimaging data from Human Connectome Project and Social neuroscience hyperscanning data; Generative models for self-assembly of simplexes of different size under geometrical constraints, chemical affinity and the presence of defects; Magnetisation-reversal processes on disordered nanonetworks with aggregated simplicial complexes and geometric spin frustrations; Self-organised criticality mechanisms that underlie collective knowlegde creation in online social systems; Agent-Based Modeling of SARS CoV-02 Epidemics simulations and analysis of stochastic bio-social processes;   dr. Bosiljka Tadić dr. Raša Pirc   Back to the top

### Activities

Scientific meetings organized by the group

 A series of meetings with an emphasis on nonequilibrium quantum dynamics, 2012 -, Krvavec, Slovenia A series of meetings on electron correlations, 2008 -, Yalta and later Odessa, Ukraine Higher-order connectivity and correlations in complex systems, 25 - 26 November 2019, The Complexity Science Hub Vienna, Austria Bound states in superconductors and interfaces, 8 - 10 April 2019, Max Planck Institute for the Physics of Complex Systems, Dresden, Germany The New Generation in Strongly Correlated Electron Systems (NGSCES) 2015, 14 - 18 September 2015, Trogir, Croatia Discrete Models of Complex Systems SUMMERSOLSTICE 2014, 22 - 25 June 2014, Jožef Stefan Institute Emergent Emotions on the Web, 20 - 21 January 2011, Jožef Stefan Institute Physical, Biological & Social Networks, 23 - 25 June 2008, Krakow, Poland Workshop Networks, Complexity & Competition, 2 - 4 May 2008, Bled, Slovenia Networks: Theory & Applications, 27 - 30 May 2007, Beijing, China Self-Assembly & Properties of Complex Patterns, 3 - 6 September 2006, Portorož, Slovenia Networks: Structure & Dynamics, 28 - 31 May 2006, University of Reading, UK Physics of Networks, 13 - 18 August 2005, Kolymbari, Crete, Greece Computational Modeling of Transport on Networks, 7 - 9 June 2004, Krakow, Poland

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### Selected Publications

 Emission of correlated jets from a driven matter-wave soliton in a quasi-one-dimensional geometry Tadej Mežnaršič, Rok Žitko, Tina Arh, Katja Gosar, Erik Zupanič, and Peter Jeglič Phys. Rev. A 101, 031601 (2020) Large-scale influence of defect bonds in geometrically constrained self-assembly Bosiljka Tadic, Milovan Suvakov, Miroslav Andjelkovic, and Geoff J. Rodgers Phys. Rev. E 102, 032307 (2020) Magnetisation Processes in Geometrically Frustrated Spin Networks with Self-Assembled Cliques Bosiljka Tadic, Miroslav Andjelkovic, Milovan Suvakov, and Geoff J. Rodgers Entropy 22, 336 (2020) The topology of higher-order complexes associated with brain hubs in human connectomes M. Andjelkovic, B. Tadic, and R. Melnik Scientific Reports 10, 17320 (2020) Resistivity and its fluctuations in disordered many-body systems: From chains to planes M. Mierzejewski, M. Środa, J. Herbrych, and P. Prelovšek Phys. Rev. B 102, 161111 (2020) Superconductivity emerging upon Se doping of the quantum spin liquid $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ Izidor Benedičič, Nejc Janša, Marion van Midden, Peter Jeglič, Martin Klanjšek, Erik Zupanič, Zvonko Jagličić, Petra Šutar, Peter Prelovšek, Dragan Mihailovič, and Denis Arčon Phys. Rev. B 102, 054401 (2020) Origin of Magnetic Ordering in a Structurally Perfect Quantum Kagome Antiferromagnet T. Arh, M. Gomilšek, P. Prelovšek, M. Pregelj, M. Klanjšek, A. Ozarowski, S. J. Clark, T. Lancaster, W. Sun, J.-X. Mi, and A. Zorko Phys. Rev. Lett. 125, 027203 (2020) Vanishing Wilson ratio as the hallmark of quantum spin-liquid models P. Prelovšek, K. Morita, T. Tohyama, and J. Herbrych Phys. Rev. Research 2, 023024 (2020) Similarity of thermodynamic properties of the Heisenberg model on triangular and kagome lattices P. Prelovšek and J. Kokalj Phys. Rev. B 101, 075105 (2020) Modeling latent infection transmissions through biosocial stochastic dynamics Bosiljka Tadic and Roderick Melnik PLOS ONE 15, 1 (2020) Spectral function of the Holstein polaron at finite temperature J. Bonča, S. A. Trugman, and M. Berciu Phys. Rev. B 100, 094307 (2019) Einstein Relation for a Driven Disordered Quantum Chain in the Subdiffusive Regime M. Mierzejewski, P. Prelovšek, and J. Bonča Phys. Rev. Lett. 122, 206601 (2019) Functional Geometry of Human Connectomes B. Tadic, M. Andjelkovic, and R. Melnik Scientific Reports 9, 12060 (2019) Spectral properties of hyperbolic nanonetworks with tunable aggregation of simplexes Marija Mitrovic Dankulov, Bosiljka Tadic, and Roderick Melnik Phys. Rev. E 100, 012309 (2019) Mottness collapse without metallisation in the domain walls of triangular-lattice Mott insulator 1T-TaS2 J. Skolimowski, Ya. Gerasimenko, and R. Žitko Phys. Rev. Lett. 122, 036802 (2019) Kondo screening in a charge-insulating spinon metal M. Gomilšek, R. Žitko, M. Klanjšek, M. Pregelj, C. Baines, Y. Li, Q. M. Zhang, and A. Zorko Nature Phys. 15, 754 (2019) Suppressed energy transport in the strongly disordered Hubbard chain Maciej Kozarzewski, Marcin Mierzejewski, and Peter Prelovšek Phys. Rev. B 99, 241113 (2019) Einstein Relation for a Driven Disordered Quantum Chain in the Subdiffusive Regime M. Mierzejewski, P. Prelovšek, and J. Bonča Phys. Rev. Lett. 122, 206601 (2019) Instability of subdiffusive spin dynamics in strongly disordered Hubbard chain M. Środa, P. Prelovšek, and M. Mierzejewski Phys. Rev. B 99, 121110 (2019) Hidden geometries in networks arising from cooperative self-assembly M. Suvakov, M. Andjelkovic, and B. Tadic Scientific Reports 8, 1987 (2018) {Yu-Shiba-Rusinov} screening of spins in double quantum dots K. Grove-Rasmussen, G. Steffensen, A. Jellinggaard, M. H. Madsen, R. Žitko, J. Paaske, and J. Nygård Nat. Commun. 9, 2376 (2018) Supercurrent in a Double Quantum Dot J. C. Estrada Saldaña, A. Vekris, G. Steffensen, R. Žitko, P. Krogstrup, J. Paaske, K. Grove-Rasmussen, and J. Nygård Phys. Rev. Lett. 121, 257701 (2018) Transient and persistent particle subdiffusion in a disordered chain coupled to bosons P. Prelovšek, J. Bonča, and M. Mierzejewski Phys. Rev. B 98, 125119 (2018) Finite-temperature properties of the extended Heisenberg model on a triangular lattice P. Prelovšek and J. Kokalj Phys. Rev. B 98, 035107 (2018) Spin Subdiffusion in the Disordered Hubbard Chain Maciej Kozarzewski, Peter Prelovšek, and Marcin Mierzejewski Phys. Rev. Lett. 120, 246602 (2018) Counting local integrals of motion in disordered spinless-fermion and Hubbard chains Marcin Mierzejewski, Maciej Kozarzewski, and Peter Prelovšek Phys. Rev. B 97, 064204 (2018) Reduced-basis approach to many-body localization P. Prelovšek, O. S. Barišić, and M. Mierzejewski Phys. Rev. B 97, 035104 (2018) Complete Many-Body Localization in the $t\text{\ensuremath{-}}J$ Model Caused by a Random Magnetic Field Gal Lemut, Marcin Mierzejewski, and Janez Bonča Phys. Rev. Lett. 119, 246601 (2017) Mechanisms of self-organized criticality in social processes of knowledge creation Bosiljka Tadic, Marija Mitrovic Dankulov, and Roderick Melnik Phys. Rev. E 96, 032307 (2017) Self-consistent approach to many-body localization and subdiffusion P. Prelovšek and J. Herbrych Phys. Rev. B 96, 035130 (2017) Density correlations and transport in models of many-body localization P. Prelovsek, M. Mierzejewski, O. Barisic, and J. Herbrych Annalen der Physik 1600362, 1 (2017) A high-temperature quantum spin liquid with polaron spins Martin Klanjšek, Andrej Zorko, Rok Žitko, Jernej Mravlje, Zvonko Jagličić, Pabitra Kumar Biswas, Peter Prelovšek, Dragan Mihailovic, and Denis Arčon Nature Physics 13, 1130 (2017) Nature of Bosonic Excitations Revealed by High-Energy Charge Carriers Jan Kogoj, Marcin Mierzejewski, and Janez Bonča Phys. Rev. Lett. 117, 227002 (2016) Algebraic Topology of Multi-Brain Connectivity Networks Reveals Dissimilarity in Functional Patterns during Spoken Communications Bosiljka Tadic, Miroslav Andjelkovic, Biljana Mileva Boshkoska, and Zoran Levnajic PLOS ONE 11, 1 (2016) Universal dynamics of density correlations at the transition to the many-body localized state M. Mierzejewski, J. Herbrych, and P. Prelovšek Phys. Rev. B 94, 224207 (2016) Absence of full many-body localization in the disordered Hubbard chain P. Prelovšek, O. S. Barišić, and M. Žnidarič Phys. Rev. B 94, 241104 (2016) Decay of density waves in coupled one-dimensional many-body-localized systems Peter Prelovšek Phys. Rev. B 94, 144204 (2016) Dynamical conductivity and its fluctuations along the crossover to many-body localization Osor S. Barišić, Jure Kokalj, Ivan Balog, and Peter Prelovšek Phys. Rev. B 94, 045126 (2016) Distinctive response of many-body localized systems to a strong electric field Maciej Kozarzewski, Peter Prelovšek, and Marcin Mierzejewski Phys. Rev. B 93, 235151 (2016) Snapshots of the retarded interaction of charge carriers with ultrafast fluctuations in cuprates S. Dal Conte, L. Vidmar, D. Golež, M. Mierzejewski, G. Soavi, S. Peli, F. Banfi, G. Ferrini, R. Comin, B. M. Ludbrook, L. Chauviere, N. D. Zhigadlo, H. Eisaki, M. Greven, S. Lupi, A. Damascelli, D. Brida, M. Capone, J. Bonča, G. Cerullo, and C. Giannetti Nature Physics 11, 421 (2015) Holon-doublon binding as the mechanism for the Mott transition Peter Prelovšek, Jure Kokalj, Zala Lenarčič, and Ross H. McKenzie Phys. Rev. B 92, 235155 (2015) Approximate conservation laws in perturbed integrable lattice models Marcin Mierzejewski, Tomaž Prosen, and Peter Prelovšek Phys. Rev. B 92, 195121 (2015) Exciton recombination in one-dimensional organic Mott insulators Zala Lenarčič, Martin Eckstein, and Peter Prelovšek Phys. Rev. B 92, 201104 (2015) Spin and thermal conductivity in a classical disordered spin chain B. Jenčič and P. Prelovšek Phys. Rev. B 92, 134305 (2015) Antiferromagnetic order in weakly coupled random spin chains J. Kokalj, J. Herbrych, A. Zheludev, and P. Prelovšek Phys. Rev. B 91, 155147 (2015) Identifying Local and Quasilocal Conserved Quantities in Integrable Systems Marcin Mierzejewski, Peter Prelovšek, and Tomaž Prosen Phys. Rev. Lett. 114, 140601 (2015) Charge recombination in undoped cuprates Zala Lenarčič and Peter Prelovšek Phys. Rev. B 90, 235136 (2014) Energy and particle currents in a driven integrable system D. Crivelli, P. Prelovšek, and M. Mierzejewski Phys. Rev. B 90, 195119 (2014) Memory function approach to in-plane anisotropic resistivity in the antiferromagnetic phase of iron arsenide superconductors Koudai Sugimoto, Peter Prelovšek, Eiji Kaneshita, and Takami Tohyama Phys. Rev. B 90, 125157 (2014) Multistage dynamics of the spin-lattice polaron formation Jan Kogoj, Zala Lenarčič, Denis Golež, Marcin Mierzejewski, Peter Prelovšek, and Janez Bonča Phys. Rev. B 90, 125104 (2014) Peltier effect in strongly driven quantum wires M. Mierzejewski, D. Crivelli, and P. Prelovšek Phys. Rev. B 90, 075124 (2014) Breakdown of the Generalized Gibbs Ensemble for Current-Generating Quenches Marcin Mierzejewski, Peter Prelovšek, and Tomaž Prosen Phys. Rev. Lett. 113, 020602 (2014) Effective $S=\frac{1}{2}$ description of the $S=1$ chain with strong easy-plane anisotropy C. Psaroudaki, J. Herbrych, J. Karadamoglou, P. Prelovšek, X. Zotos, and N. Papanicolaou Phys. Rev. B 89, 224418 (2014) Optical response of highly excited particles in a strongly correlated system Zala Lenarčič, Denis Golež, Janez Bonča, and Peter Prelovšek Phys. Rev. B 89, 125123 (2014) Co-Evolutionary Mechanisms of Emotional Bursts in Online Social Dynamics and Networks Bosiljka Tadic, Vladimir Gligorijevic, Marija Mitrovic, and Milovan Suvakov Entropy 15, 5084 (2013) Local Spin Relaxation within the Random Heisenberg Chain J. Herbrych, J. Kokalj, and P. Prelovšek Phys. Rev. Lett. 111, 147203 (2013) Ultrafast Charge Recombination in a Photoexcited Mott-Hubbard Insulator Zala Lenarčič and Peter Prelovšek Phys. Rev. Lett. 111, 016401 (2013) Eigenvalue Statistics of Reduced Density Matrix during Driving and Relaxation M. Mierzejewski, T. Prosen, D. Crivelli, and P. Prelovšek Phys. Rev. Lett. 110, 200602 (2013) Eigenstate thermalization within isolated spin-chain systems R. Steinigeweg, J. Herbrych, and P. Prelovšek Phys. Rev. E 87, 012118 (2013) Relaxation Dynamics of the Holstein Polaron Denis Golež, Janez Bonča, Lev Vidmar, and Stuart A. Trugman Phys. Rev. Lett. 109, 236402 (2012) Spin hydrodynamics in the $S=\frac{1}{2}$ anisotropic Heisenberg chain J. Herbrych, R. Steinigeweg, and P. Prelovšek Phys. Rev. B 86, 115106 (2012) Coexistence of anomalous and normal diffusion in integrable Mott insulators R. Steinigeweg, J. Herbrych, P. Prelovšek, and M. Mierzejewski Phys. Rev. B 85, 214409 (2012) Dielectric Breakdown in Spin-Polarized Mott Insulator Zala Lenarčič and Peter Prelovšek Phys. Rev. Lett. 108, 196401 (2012) Quantitative analysis of bloggers' collective behavior powered by emotions Marija Mitrovic, Georgios Paltoglou, and Bosiljka Tadic Journal of Statistical Mechanics: Theory and Experiment 2011, P02005 (2011) Finite-temperature Drude weight within the anisotropic Heisenberg chain J. Herbrych, P. Prelovšek, and X. Zotos Phys. Rev. B 84, 155125 (2011) Integrable Mott Insulators Driven by a Finite Electric Field Marcin Mierzejewski, Janez Bonča, and Peter Prelovšek Phys. Rev. Lett. 107, 126601 (2011) Nonequilibrium Quantum Dynamics of a Charge Carrier Doped into a Mott Insulator M. Mierzejewski, L. Vidmar, J. Bonča, and P. Prelovšek Phys. Rev. Lett. 106, 196401 (2011) Nonequilibrium dynamics of the Holstein polaron driven by an external electric field Lev Vidmar, Janez Bonča, Marcin Mierzejewski, Peter Prelovšek, and Stuart A. Trugman Phys. Rev. B 83, 134301 (2011) Modeling collective charge transport in nanoparticle assemblies Milovan Suvakov and Bosiljka Tadic Journal of Physics: Condensed Matter 22, 163201 (2010) Nonlinear Current Response of an Isolated System of Interacting Fermions Marcin Mierzejewski and Peter Prelovšek Phys. Rev. Lett. 105, 186405 (2010) Conductivity in a disordered one-dimensional system of interacting fermions O. S. Barišić and P. Prelovšek Phys. Rev. B 82, 161106 (2010) Dynamical central peak and spinon deconfinement in frustrated spin chains J. Kokalj and P. Prelovšek Phys. Rev. B 82, 060406 (2010) Thermal transport in a spin-$\frac{1}{2}$ Heisenberg chain coupled to a magnetic or nonmagnetic impurity A. Metavitsiadis, X. Zotos, O. S. Barišić, and P. Prelovšek Phys. Rev. B 81, 205101 (2010) Phenomenological theory of the anomalous normal-state transport properties of iron pnictides P. Prelovšek and I. Sega Phys. Rev. B 81, 115121 (2010)

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### Selected Collaborations

 S. A. Trugman, Center for Integrated Nano technologies, Los Alamos National Laboratory, NM USA T. Tohyama, Tokyo University of Science, Tokyo, Japan M. Mierzejewski, Department of Theoretical Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology J. C. Estrada Saldaña, J. Paaske, K. Grove-Rasmussen, J. Nygård, QDev, Center for quantum devices, University of Copenhagen, Denmark J. Vučičević, D. Tanasković, Institute of Physics, Belgrade, Serbia B. S. Shastry, University of California Santa Cruz, USA M. Fabrizio, SISSA, Trieste, Italy R. Melnik, Department of Mathematics, Wilfrid Laurier University, Waterloo, ON, Canada M. Mitrović Dankulov, Scientific Computing Lab, Institute of Physics, Belgrade, Serbia G. J. Rodgers, Brunel University London, UK M. Šuvakov, Institute of Physics, Belgrade, Serbia and Mayo Clinics, Rochester, USA S. Thurner, Medical University Vienna and Complexity Science Hub Vienna, Austria

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### Alumni and former associates (subsequent affiliation)

 Kristjan Haule (Rutgers University) Matjaž Zemljič (Banka Slovenije) Janez Jaklič (Cadence Design Systems, Inc.)

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The group is funded in part by the Slovenian Research Agency (research core funding No. P1-0044).