Organisers : Benjamin Doyon (lead organiser), Alessia Annibale, Yan Fyodorov, Reimer Kühn, Izaak Neri, Gabriele Sicuro
The talks of the Complex & Disordered Systems workshop will be held in room S-1.04 of the Strand Building.
Tea & Coffee will be offered in the Bush House Arcade.
The talks of the Complex & Disordered Systems workshop will be held in room S-1.04 of the Strand Building.
Tea & Coffee will be offered in the Bush House Arcade.
Invited speakers
Gennady El
Northumbria U. UK |
Marylou Gabrié
École polytechnique France |
Bertrand
Lacroix A Chez Toine KCL UK |
Satya Majumdar
U. Paris-Sud, Orsay France |
José Moran
Oxford U. UK |
Paola Ruggiero
KCL UK |
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Tuesday 7th 14.15 - 15.05: Marylou Gabrié
15.10 - 16.00: Bertrand Lacroix-A-Chez-Toine 16.00 - 16.40: Tea & Coffee [BH(N) Arcade] 16.40 - 17.30: Gennady El |
Wednesday 8th 14.15 - 15.05: Satya Majumdar
15.10 - 16.00: Paola Ruggiero 16.00 - 16.40: Tea & Coffee [BH(N) Arcade] 16.40 - 17.30: José Moran |
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Marylou Gabrié
Statistical Mechanics and Machine Learning Interactions: Enhancing Sampling with Learning Abstract. In many applications in computational sciences, one seeks to compute expectations on complex high-dimensional distributions. In this context, Monte Carlo methods share a long history of interaction with Statistical Physics. In this talk, I will review some recent works exploring further opportunities in enhancing sampling with machine learning. In particular, these methods rely largely on deep generative models which are very flexible probabilistic models. We will see how learning can lead to drastic acceleration of MCMC convergence, but also how blending expert knowledge is sometimes key for success. |
Satya Majumdar
Stochastic resetting Abstract. A stochastic process, when interrupted at random epochs and reset to its initial condition, reaches a nonequilibrium stationary state. The approach to the stationary state is accompanied by an unusual ‘dynamical phase transition’. Moreover, the mean first-passage time to a fixed target becomes a minimum at an optimal value of the resetting rate. This makes the diffusive search process more efficient. New experiments in optical traps have verified some of the theoretical predictions, but also have raised new interesting questions. Stochastic resetting has emerged in recent years as an exciting field of research in nonequilibrium statistical physics. In this talk, I’ll give an overview of this rapidly evolving field. At the end, I'll talk about some recent work on resetting Brownian bridges. |
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Bertrand Lacroix-A-Chez-Toine
Random landscape built by superposition of random plane waves Abstract. In this talk, I will present exact recent results on a new model of random landscape in N dimensions consisting of a harmonic confinement and a random function built as a superposition of M>N random plane waves. We compute the total annealed complexity (rate of exponential growth of average number of stationary with the dimension) in the limit of large N,M with the ratio a=M/N fixed. In contrast to previously studied model such as the Gaussian random landscape, the complexity remains strictly positive for any finite value of the confinement strength. Hence, there is no "topology trivialisation transition" for this model, which seems to be a representative of a distinct class of universality. |
Paola Ruggiero
Entanglement, area law & its violation in many-body systems Abstract. At the center of the debate on quantum mechanics since its foundations, entanglement is arguably not one but rather the distinguishing signature of the quantum world. In this talk I will introduce this concept and motivate why it is still interesting and subject of ongoing research. I will argue that the problem of quantify entanglement is highly non-trivial, especially in the context of many-body systems. At the same time, I will give some general existing results, in the form of conjecture or theorem, for the so-called “area law” of entanglement, and discuss more recent advances about its violation, with particular focus on disordered/inhomogeneous quantum many-body systems. |
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Gennady El
Dispersive hydrodynamics of soliton condensates in integrable systems Abstract. Soliton gases in integrable dispersive systems have attracted a significant interest in connection with the general subject of ``integrable turbulence'' (Zakharov, 2009) and recent experiments in water waves and fibre optics. On the other hand, the recently established striking parallels with generalised hydrodynamics (GHD) open new interesting perspectives for the theories of dispersive shock waves and modulational instability. In my talk, I will provide a dictionary between GHD and kinetic theory of soliton gas and consider a special limit of dense soliton gases termed ``soliton condensates''. I will show that in this limit, the kinetic equation describing large-scale dynamics of non-equilibrium KdV soliton... condensates reduces to the multiphase Whitham modulation equations derived by Flaschka, Forest and McLaughlin (1980) and Lax and Levermore (1983). I will then present exact solutions for several Riemann problems for soliton condensates and identify the resulting dynamics with generalised rarefaction and dispersive shock waves. I will also present numerical results for "diluted" soliton condensates exhibiting rich incoherent nonlinear wave behaviours. Finally, if time permits, I will show how the soliton condensate dynamics for the focusing nonlinear Schrödinger equation sheds light on the nature of spontaneous modulational instability. The talk is based on recent joint theoretical and experimental works with T. Bonnemain, T. Congy, B. Doyon, S. Randoux, G. Roberti, P. Suret and A. Tovbis. |
José Moran
Out of equilibrium economies Abstract. An economy is a complex assembly of interacting agents. Firms are entwined in complex production relationships, needing to buy inputs from one another in order to produce; households sell their labour to these firms in exchange for a wage, which they either spend buying goods or save into accounts that are then used by banks to invest in economic activities. For all of these activities, agents are perpetually trying to coordinate with others, and trying to anticipate what is going to happen. In trying to understand the outcome of this coordination process, most economic analyses have focused in comparative statics: given a set of economic relationships, they describe and solve sets of equations that describe an economic equilibrium, where agents' have reached perfect coordination. ... To understand the effect of an economic shock, like the Ukraine war or a pandemic, new equilibrium conditions are introduced, and the resulting new equilibrium is compared to the previous. However, there is very little understanding about the dynamics through which an equilibrium is actually reached. In this talk, I shall present a simplified model of an economy where explicit out-of-equilibrium dynamics are introduced, producing results far richer than a simple convergence to equilibrium. I will discuss links with other existing models in the economic literature and how this relates to ongoing research in complexity (macro)economics. |