Fluctuations far from equilibrium, large deviations and integrability

par Kirone Mallick (IPHT, CEA Saclay)

jeudi 23 avr. 2026, 11:00 → 12:00 Europe/Paris

Auditorium (LAPTh)

Many natural systems  continously exchange  matter, energy or
information with their surroundings.
 Due to these  permanent  fluxes   that break time-reversal invariance,
such systems are far from thermodynamic equilibrium  and lie beyond
 the  traditional principles of equilibrium statistical 
mechanics. For instance,  the steady state of a
conducting rod  in contact with two  reservoirs at different temperatures
can not be accounted for 
by  any of the classical  ensembles of statistical  mechanics.

The quest for  a unified approach to  non-equilibrium behaviour,
that would go far beyond  linear response  theory, has remained an open
problem for many years.
In the  last decades,  the  discoveries  of certain  universal laws
and    exact
solutions of  paradigmatic models have 
unveiled  some of the mysteries of  non-equilibrium   physics.
 In parallel, large deviation theory  has emerged as an  adequate framework
to formulate  general   properties like the fluctuation relations, 
and variational principles such as the Macroscopic Fluctuation
Theory of  G. Jona-Lasinio and his collaborators.

 The goal of this talk
is  to present some of these concepts and to explain how   the interplay
 of elegant  
integrability techniques,  either  quantum 
(Bethe Ansatz) or classical   (inverse scattering method),  has led
to  a quantitative understanding of  
non-equilibrium fluctuations at various levels:  microscopic,
mesoscopic and macroscopic.