SFB 1432:  Fluctuations and Nonlinearities in Classical and Quantum Matter beyond Equilibrium

• Subject Area: Physics ; Chemistry ; Mathematics
• Term: since 2021
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 425217212

Within the framework of the proposed CRC, we will investigate the dynamics of systems influenced by fluctuations far from equilibrium or determined by strongly nonlinear interactions. In both classical and quantum physics, mostly average quantities have been studied in the past. If fluctuating properties were concerned, they were often investigated within the approximation of local equilibrium or linear response. We will harness recent developments in experiment, simulations, and theory to directly explore statistical properties of physical quantities, concentrating especially on advanced aspects such as non-Gaussian statistics, extreme nonlinearities, quantum fluctuations and entanglement, or completely dissipation-induced dynamics. In all these cases, fluctuations can lead to entirely novel physical phenomena and, potentially, to new functionalities. One key element of this CRC is the combination of different approaches from classical and quantum physics. We will work out the common grounds and differences of fluctuations and nonlinear behavior occurring in the fields of soft matter, quantum transport, magnetism, nano- and micromechanics, and ultrafast phenomena. While classical thermal fluctuations as well as quantum vacuum fluctuations dominate the equilibrium state, creating a non-standard environment or driving far beyond equilibrium will allow us to enter uncharted territory, possibly comprising processes such as dynamical phase transitions or switching phenomena. We also expect a better understanding of the quantum-to-classical transition for fluctuations in nonequilibrium situations, for which no generally accepted criteria exist to date. Extreme nonlinearities in well-characterized systems will open novel opportunities to investigate the dynamics, e.g., in atomic and nanomechanical systems. We will study this interplay between fluctuations and nonlinearities in out-of-equilibrium situations in a broad spectrum of hybrid systems combining charges and fields, as well as collective excitations based on spin and motional degrees of freedom. Our efforts combine the expertise and methods from experimental and theoretical physics with physical chemistry and mathematics. We will create an innovative framework, in which studies of fluctuations and nonlinearities lead to a deeper understanding of both classical and quantum matter. Thus, by advancing these concepts to valuable tools in generating knowledge, we will open up a new way to scientific progress.

• DFG Programme: Collaborative Research Centres

Current projects

• A01 - Coulomb correlations and non-Poissonian statistics in attosecond picotransport (Project Head Leitenstorfer, Alfred )
• A02 - Charge fluctuations in superconducting single electron transistors (Project Heads Belzig, Wolfgang ;  Scheer, Elke )
• A03 - Quantum transport in the presence of engineered quantum fields (Project Head Belzig, Wolfgang )
• A04 - Fluctuations in few-electron pulses between the quantum limit and space-charge regime (Project Head Baum, Peter )
• A05 - Quantum dynamics and measurement of radiation in the time domain (Project Head Burkard, Guido )
• A06 - Time-domain quantum statistics of nonclassical mid-infrared electric fields (Project Head Leitenstorfer, Alfred )
• B01 - Spin shot noise and hybrid noise measurements (Project Head Gönnenwein, Sebastian )
• B02 - Role of fluctuations in magnetic transport (Project Head Nowak, Ulrich )
• B03 - Microscopic probes of critical spin fluctuations in 2D magnets (Project Head Müller, Martina )
• B04 - Excited states and dynamics of current-driven molecular spin systems (Project Heads Fonin, Mikhail ;  Winter, Rainer )
• B05 - Space-time imaging of spontaneous reaction and spin dynamics by ultrafast double-probe electron microscopy (Project Head Baum, Peter )
• B06 - High-frequency spin noise dynamics in magnetically ordered systems (Project Heads Gönnenwein, Sebastian ;  Nowak, Ulrich )
• B07 - Femtosecond quantum magnonics in a nonlinear regime far from equilibrium (Project Head Bossini, Davide )
• C01 - Fluctuation-induced nonlinear dynamics of nanomechanical systems (Project Head Weig, Eva M. )
• C02 - Strongly driven nanomechanical systems: classical and quantum (Project Heads Belzig, Wolfgang ;  Burkard, Guido )
• C03 - Strongly nonlinear multi-dimensional resonators (Project Head Scheer, Elke )
• C04 - Numerical optimization methods for the identification and control of fluctuating systems (Project Heads Ciaramella, Gabriele ;  Volkwein, Stefan )
• C05 - Driven particles in strongly coupled non-Markovian baths (Project Heads Bechinger, Clemens ;  Krüger, Matthias )
• C06 - Driven activation in a nonequilibrium bath (Project Head Fuchs, Matthias )
• C07 - Stress correlations in complex fluids (Project Heads Fuchs, Matthias ;  Zumbusch, Andreas )
• C08 - Stationary phases and dynamic activation in parametrically-driven stochastic resonators (Project Head Zilberberg, Ph.D., Oded )
• MGK - Integrated Research Training Group Fluctuations and Nonlinearities (FaN) (Project Heads Müller, Martina ;  Weig, Eva M. )
• Z - Central Tasks of the Collaborative Research Center (Project Head Belzig, Wolfgang )

• Applicant Institution: Universität Konstanz
• Participating University: Georg-August-Universität Göttingen
• Spokesperson: Professor Dr. Wolfgang Belzig