Many natural systems remain far from thermodynamic equilibrium by exchanging matter, energy or information with their environment. As these transfers break the invariance of time reversal, these processes escape traditional thermodynamics and their intrinsic fluctuations do not follow the principles of statistical mechanics at equilibrium. Understanding the physics of classical or quantum processes far from equilibrium is a major theoretical challenge.
Outside thermodynamics, equilibrium state functions, such as entropy or free energy, become unsuitable and are replaced by the unifying concept of large deviation potentials. The mathematical study of different levels of large deviations and their properties, as well as their consequences for macroscopic fluctuations in various classical processes, is the focus of several projects at the IPhT (Glauber-Ising chains, record statistics, stochastic resetting, jamming and metastability, interacting particle systems, Polya walks, temperature quenching, etc.).
Ideas from non-equilibrium physics play a crucial role in the design of efficient optimisation algorithms, such as stochastic gradient descent, used to train artificial neural networks for deep learning, and more generally in exploring the complex dynamics of glassy systems. IPhT researchers are also working on algorithms inspired by optimal transport to generate transition paths for protein folding.
On the quantum side, the institute also has activities on dissipative N-body quantum systems and on the role of quantum measurements in simple models, such as quantum exclusion processes. These models constitute toolboxes for studying the interaction between decoherence and measurement. Finally, the eigenstate thermalization hypothesis (ETH) and its relationship with quantum chaos is another research direction explored at the IPhT.
Scientific staff
Kirone MALLICK
Laura FOINI
Grégoire MISGUICH
Jean-Marc LUCK
Claude GODRÈCHE
Michel BAUER
Cecile MONTHUS
Henri ORLAND
Pierfrancesco URBANI