TRR 360:  Constrained Quantum Matter

• Subject Area: Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 492547816

Recent advances in the understanding of the organizing principles of quantum matter, alongside with breakthrough developments of experimental methodology, provide an excellent starting point for research on the design and control of emergent quantum phases. At the same time, complex quantum materials are developing into a powerful platform for the exploration of conceptual challenges from quantum information theory to non-equilibrium physics. The proposed Transregio on Constrained Quantum Matter (ConQuMat) will address such challenges by creating, detecting, and controlling novel quantum states via carefully chosen constraints, including spin-momentum locking, gauge structures, and kinetic constraints. The basic guiding principle is that a reduction of the degrees of freedom through suitable constraints can yield exciting physical phenomena. Our approach will facilitate the realization as well as detection of quantum entanglement and the exploration of novel quantum effects in solid state materials with the long-term goal to stabilize them at practical conditions, thus fostering applications on a broad scale. To reach this goal, we bring together key expertise in three major directions of quantum matter research - magnetic band topology, entangled states of quantum matter, and non-equilibrium dynamics - each of them representing one research area of ConQuMat. The individual projects within these three pillars will contribute to the mission by exploring the interplay between the constraints above from different vantage points. The multi-faceted research on quantum matter to be pursued in ConQuMat requires an exceptionally broad range of key competences, comprising the full spectrum of theoretical methods together with a plethora of advanced experimental techniques available either on the laboratory scale or at large-scale facilities. The groups working at the two main partner universities, the University of Augsburg and the Technical University of Munich, not only have a long and very successful track-record in applying advanced methods for quantum matter research, but also possess a well-documented potential in pioneering method developments. In order to complete the range of required competences, ConQuMat also involves world-class scientists with unique expertise from external institutions. The novel concept envisaged in ConQuMat will advance the fundamental understanding of quantum matter and allow us to exploit constraints to create novel quantum states.

• DFG Programme: CRC/Transregios
• International Connection: Japan

Current projects

• A01 - Tuning topological electronic states and topological magnons (Project Heads Deisenhofer, Joachim ;  Kuntscher, Christine ;  Kézsmárki, István )
• A02 - Spin-charge conversion and topological magnons in magnetic Weyl semimetals (Project Heads Albrecht, Manfred ;  Back, Christian ;  Chen, Lin )
• A03 - Atomic-scale visualization of magnetic-field-tuned states in topological structures (Project Heads Huang, Dennis ;  Takagi, Hidenori )
• A04 - Imaging mesoscale magnetic textures in topological magnets (Project Heads Kézsmárki, István ;  Litzius, Kai )
• A05 - Optical conductivities and entanglement in magnetic topological semimetals (Project Heads Chioncel, Liviu ;  Heyl, Markus Philip Ludwig )
• A06 - Global band topology: from point crossings to nodal planes (Project Heads Classen, Laura ;  Schnyder, Andreas ;  Wilde, Marc )
• B01 - New faces of Kitaev materials: chemical, pressure, and strain tuning (Project Heads Gegenwart, Philipp ;  Jesche, Anton ;  Tsirlin, Alexander )
• B02 - Photon scattering from spin-orbit materials (Project Heads Benckiser, Eva ;  Hepting, Matthias ;  Keimer, Bernhard )
• B03 - Dynamics of rare-earth-based frustrated magnets (Project Heads Gegenwart, Philipp ;  Schneidewind, Astrid ;  Tsirlin, Alexander )
• B04 - Magnetic resonance spectroscopy on quantum spin liquids and Weyl semimetals (Project Heads Büttgen, Norbert ;  Krug von Nidda, Hans-Albrecht )
• B05 - Thermal conductivity and thermal Hall effect of frustrated magnets (Project Heads Gegenwart, Philipp ;  Hirschberger, Max )
• B06 - Dynamics of correlated quantum magnets (Project Heads Heyl, Markus Philip Ludwig ;  Knolle, Johannes ;  Pollmann, Frank )
• C01 - Kinetic arrest and quantum annealing in model systems (Project Heads Franz, Christian ;  Pfleiderer, Christian )
• C02 - Unconventional dynamics at the mesoscale in constrained spin systems (Project Heads Back, Christian ;  Büttner, Felix ;  Kézsmárki, István )
• C03 - Dynamically driven quantum correlations (Project Heads Hübl, Hans ;  Pfleiderer, Christian ;  Wilde, Marc )
• C04 - Ultrastrong matter-magnon coupling phenomena (Project Heads Deisenhofer, Joachim ;  Kollar, Marcus )
• C05 - Constrained quantum many-body dynamics (Project Heads Bañuls, Mari Carmen ;  Knap, Michael ;  Pollmann, Frank )
• C06 - Manipulating correlated quantum magnets by a periodic drive (Project Heads Knap, Michael ;  Knolle, Johannes )
• C07 - Cavity-based control of quantum magnets: frustration, entanglement, and competing orders (Project Heads Benito, Monica ;  Hübl, Hans ;  Piazza, Ph.D., Francesco )
• MGK - Integrated research training group (Project Heads Benckiser, Eva ;  Büttner, Felix ;  Knolle, Johannes ;  Pfleiderer, Christian )
• Z - Central tasks (Project Head Kézsmárki, István )
• Ö - ConQuMat goes public (public relations) (Project Heads Krey, Olaf ;  Menner, Marietta )

• Applicant Institution: Universität Augsburg
• Co-Applicant Institution: Technische Universität München (TUM)
• Participating Institution: Komitee Forschung mit Neutronen (KFN); c/o Forschungszentrum Jülich GmbH; Max-Planck-Institut für Festkörperforschung (MPI-FKF); Max-Planck-Institut für Quantenoptik (MPQ); Bayerische Akademie der Wissenschaften; Walther-Meißner-Institut für Tieftemperaturforschung
• Participating University: The University of Tokyo; Universität Leipzig
• Spokesperson: Professor Dr. István Kézsmárki