Periodic Reporting for period 3 - FASTCORR (Ultrafast dynamics of correlated electrons in solids)
Période du rapport: 2023-06-01 au 2024-11-30
In FASTCORR, we tackle significant scientific challenge related to understanding ultrafast dynamics in materials with strongly correlated electrons. Experimental advances using modern photon sources such as high-intensity lasers and X-ray free electron lasers (XFEL) have produced unprecedented results that require a new theoretical framework for interpretation. Traditional methods fall short when it comes to describing the complex light-matter interactions at femtosecond or even sub-femtosecond timescales, especially in materials where electron correlation effects dominate, such as superconductors and magnetic materials.
Understanding these ultrafast processes is crucial for the development of new technologies, that could potentially lead to advancements in electronics operating at petahertz speeds, new materials with superior functional properties. The insights gained from this research may also pave the way for innovations in areas like energy harvesting, information technology, and quantum materials, driving societal progress in both fundamental science and applied technology.
Overall Objectives:
1. Theoretical Development: The project aims to create a new theoretical framework, expanding on dynamical mean-field theory and its generalizations, e.g. the dual fermion and dual boson theory, to address out-of-equilibrium situations. This involves developing tools that go beyond existing linear theories to handle complex, nonlinear interactions in driven quantum systems.
2. Practical Tools and Software: FASTCORR intends to develop high-performance computational software that will allow researchers worldwide to simulate and predict ultrafast phenomena in strongly correlated materials. These tools will be made freely available, enabling widespread use in the scientific community.
3. Experimental Validation: The theoretical tools developed will be validated through comparison with experimental data, particularly from pump-probe spectroscopy techniques. This collaboration between theory and experiment is central to bridging the knowledge gap and advancing our understanding of ultrafast dynamics in correlated electron systems
FASTCORR will result in novel high-performance software that will be freely distributed. These computational tools enable designed and targeted calculations for driven materials where the electronic structure is determined by strong correlation effects. The developed theory is used hand in hand with world-leading experimental works in the field of pump-probe measurements and spectroscopy, e.g. as investigated at X-ray free-electron laser laboratories.
Understanding these ultrafast processes is crucial for the development of new technologies, that could potentially lead to advancements in electronics operating at petahertz speeds, new materials with superior functional properties. The insights gained from this research may also pave the way for innovations in areas like energy harvesting, information technology, and quantum materials, driving societal progress in both fundamental science and applied technology.
Overall Objectives:
1. Theoretical Development: The project aims to create a new theoretical framework, expanding on dynamical mean-field theory and its generalizations, e.g. the dual fermion and dual boson theory, to address out-of-equilibrium situations. This involves developing tools that go beyond existing linear theories to handle complex, nonlinear interactions in driven quantum systems.
2. Practical Tools and Software: FASTCORR intends to develop high-performance computational software that will allow researchers worldwide to simulate and predict ultrafast phenomena in strongly correlated materials. These tools will be made freely available, enabling widespread use in the scientific community.
3. Experimental Validation: The theoretical tools developed will be validated through comparison with experimental data, particularly from pump-probe spectroscopy techniques. This collaboration between theory and experiment is central to bridging the knowledge gap and advancing our understanding of ultrafast dynamics in correlated electron systems
FASTCORR will result in novel high-performance software that will be freely distributed. These computational tools enable designed and targeted calculations for driven materials where the electronic structure is determined by strong correlation effects. The developed theory is used hand in hand with world-leading experimental works in the field of pump-probe measurements and spectroscopy, e.g. as investigated at X-ray free-electron laser laboratories.
The FASTCORR project is performing well, showing substantial progress across multiple work packages and collaborations. The project has successfully advanced both fundamental theory and practical methodologies related to ultrafast dynamics in strongly correlated materials. Key developments have been achieved in areas such as quantum many-body systems, magnetic interactions, and optical spectroscopy. The collaboration between nodes has been fruitful, leading to innovative research outputs and over 110 publications in peer reviewed articles, many in high-profile journals such as Review of Modern Physics, Physical Review Letters, Nature and Science.
Key Highlights:
1. A significant achievement is the development of multidimensional spectroscopy techniques for strongly correlated materials, as published in Nature Photonics (2024). This collaboration between the Nijmegen and Hamburg groups shows how the optical response of correlated systems can be measured at sub-cycle IR timescales, revealing intricate many-body dynamics.
2. Uppsala University, in collaboration with other partners, has successfully integrated time-dependent density functional theory (TDDFT) with element-specific EUV probes. This combination allows for unprecedented precision in distinguishing same-site and intersite spin transfers in ultrafast spin dynamics, published in Science Advances (2023). This work enhances the understanding of energy-efficient spintronic devices.
3. The Hamburg node made substantial progress by implementing exact diagonalization techniques for non-equilibrium quantum dynamics. Although the system size limitations pose challenges, the developed methods are critical for evaluating time-dependent higher-order correlation functions in quantum systems.
4. The Nijmegen and Uppsala nodes collaborated on the study of quantum skyrmions and quantum Zeno effects in Heisenberg models. These findings contribute to the understanding of magnetic materials and the potential for quantum state manipulation of topologically protected states relevant for future technologies.
5. To study the complex dynamics in quantum quenches, the Hamburg and Nijmegen nodes has studied dynamics of fracton matter, demonstrating fractal wavefront formation. Additionally, the Hamburg and Nijmegen groups explored the amplification of superconductivity in fractal nanoflakes, providing a new perspective on unconventional superconductors.
6. The three nodes have condensed the long-standing research effort into magnetic interactions in solids and significantly expands on the theoretical framework for out-of-equilibrium situations in to a review article published in Reviews of Modern Physics (2023).
7. In collaboration with Radboud University, the project revealed insights into long-range magnetic order from spin glass behaviors, as published in Nature Physics (2022).
Key Highlights:
1. A significant achievement is the development of multidimensional spectroscopy techniques for strongly correlated materials, as published in Nature Photonics (2024). This collaboration between the Nijmegen and Hamburg groups shows how the optical response of correlated systems can be measured at sub-cycle IR timescales, revealing intricate many-body dynamics.
2. Uppsala University, in collaboration with other partners, has successfully integrated time-dependent density functional theory (TDDFT) with element-specific EUV probes. This combination allows for unprecedented precision in distinguishing same-site and intersite spin transfers in ultrafast spin dynamics, published in Science Advances (2023). This work enhances the understanding of energy-efficient spintronic devices.
3. The Hamburg node made substantial progress by implementing exact diagonalization techniques for non-equilibrium quantum dynamics. Although the system size limitations pose challenges, the developed methods are critical for evaluating time-dependent higher-order correlation functions in quantum systems.
4. The Nijmegen and Uppsala nodes collaborated on the study of quantum skyrmions and quantum Zeno effects in Heisenberg models. These findings contribute to the understanding of magnetic materials and the potential for quantum state manipulation of topologically protected states relevant for future technologies.
5. To study the complex dynamics in quantum quenches, the Hamburg and Nijmegen nodes has studied dynamics of fracton matter, demonstrating fractal wavefront formation. Additionally, the Hamburg and Nijmegen groups explored the amplification of superconductivity in fractal nanoflakes, providing a new perspective on unconventional superconductors.
6. The three nodes have condensed the long-standing research effort into magnetic interactions in solids and significantly expands on the theoretical framework for out-of-equilibrium situations in to a review article published in Reviews of Modern Physics (2023).
7. In collaboration with Radboud University, the project revealed insights into long-range magnetic order from spin glass behaviors, as published in Nature Physics (2022).
The progress of the FASTCORR project has addressed many of the original goals stated in the project proposal, yet several areas still require progress beyond the current state of the art to fully achieve all the objectives. Currently, we focus on the following points:
• Our effort on Non-Equilibrium DMFT for Real-Time Dynamics has made significant advances, but there are still substantial challenges in scaling this method to handle larger systems and longer time scales. Exact diagonalization methods face limitations in system size due to exponential growth in the state space, and embedding methods require computational resources that grow exponentially with time. The numerical techniques to deal with the computational cost involved has to be improved. Current approaches, while successful in simpler models, are not fully scalable for more complex, realistic materials.
• The theoretical advancements in dual fermion and dual boson theory are on track, but more work is needed to fully implement these approaches for out-of-equilibrium phenomena, especially in the context of time-resolved spectroscopy. The Nijmegen/Hamburg teams has developed a generic solver, but extending these methods to real-time dynamics and practical applications remains a challenging task.
• The Schwinger-Baym-Kadanoff-Keldysh non-equilibrium Green’s function formalism is a cornerstone for handling dynamics in quantum systems. The project has made steps towards its application in driven systems, but challenges remain in efficiently calculating two-time Green's functions in a computationally feasible way for real materials. Our activities in the Örebro node focuses on this area.
• The Uppsala nodes use of machine learning and data filtering techniques to identify new materials has shown promise, but refining these techniques to better differentiate strongly correlated materials from non-correlated ones remains a significant challenge.
• Our effort on Non-Equilibrium DMFT for Real-Time Dynamics has made significant advances, but there are still substantial challenges in scaling this method to handle larger systems and longer time scales. Exact diagonalization methods face limitations in system size due to exponential growth in the state space, and embedding methods require computational resources that grow exponentially with time. The numerical techniques to deal with the computational cost involved has to be improved. Current approaches, while successful in simpler models, are not fully scalable for more complex, realistic materials.
• The theoretical advancements in dual fermion and dual boson theory are on track, but more work is needed to fully implement these approaches for out-of-equilibrium phenomena, especially in the context of time-resolved spectroscopy. The Nijmegen/Hamburg teams has developed a generic solver, but extending these methods to real-time dynamics and practical applications remains a challenging task.
• The Schwinger-Baym-Kadanoff-Keldysh non-equilibrium Green’s function formalism is a cornerstone for handling dynamics in quantum systems. The project has made steps towards its application in driven systems, but challenges remain in efficiently calculating two-time Green's functions in a computationally feasible way for real materials. Our activities in the Örebro node focuses on this area.
• The Uppsala nodes use of machine learning and data filtering techniques to identify new materials has shown promise, but refining these techniques to better differentiate strongly correlated materials from non-correlated ones remains a significant challenge.