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Matthieu Wyart

Cette personne a quitté l’EPFL

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Publications associées (62)

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How collective asperity detachments nucleate slip at frictional interfaces

Matthieu Wyart, Thomas Willem Jan de Geus, Marko Popovic, Wencheng Ji

Sliding at a quasi-statically loaded frictional interface can occur via macroscopic slip events, which nucleate locally before propagating as rupture fronts very similar to fracture. We introduce a microscopic model of a frictional interface that includes ...

National Academy of Sciences2019

Dynamical heterogeneities of thermal creep in pinned interfaces

Matthieu Wyart, Thomas Willem Jan de Geus

Disordered systems under applied loading display slow creep flows at finite temperature. Renormalization group arguments predicted that creep proceeds via thermal avalanches of activated events. Recently, thermal avalanches were argued to control the dynam ...

2025

Unsteady flow and particle migration in dense, non-Brownian suspensions

Matthieu Wyart

We present experimental results on dense corn-starch suspensions as examples of non-Brownian, nearly hard particles that undergo continuous and discontinuous shear thickening (DST) at intermediate and high densities, respectively. Our results offer strong ...

Journal Rheology Amer Inst Physics2016

Model for the erosion onset of a granular bed sheared by a viscous fluid

Matthieu Wyart

We study theoretically the erosion threshold of a granular bed forced by a viscous fluid. We first introduce a model of interacting particles driven on a rough substrate. It predicts a continuous transition at some threshold forcing theta(c), beyond which ...

Amer Physical Soc2016

Scaling description of generalization with number of parameters in deep learning

Matthieu Wyart, Clément Hongler, Mario Geiger, Franck Raymond Gabriel, Stefano Spigler, Arthur Ulysse Jacot-Guillarmod, Levent Dogus Sagun

Supervised deep learning involves the training of neural networks with a large number N of parameters. For large enough N, in the so-called over-parametrized regime, one can essentially fit the training data points. Sparsitybased arguments would suggest th ...

IOP PUBLISHING LTD2020

Effect of friction on dense suspension flows of hard particles

Matthieu Wyart, Eric DeGiuli

We use numerical simulations to study the effect of particle friction on suspension flows of non-Brownian hard particles. By systematically varying the microscopic friction coefficient mu(p) and the viscous number J, we build a phase diagram that identifie ...

Amer Physical Soc2017

Mean-field description for the architecture of low-energy excitations in glasses

Matthieu Wyart, Thomas Willem Jan de Geus, Elisabeth Agoritsas, Wencheng Ji

In amorphous materials, groups of particles can rearrange locally into a new stable configuration. Such elementary excitations are key as they determine the response to external stresses, as well as to thermal and quantum fluctuations. Yet, understanding w ...

2022

A phase transition in diffusion models reveals the hierarchical nature of data

Matthieu Wyart, Alessandro Favero, Antonio Sclocchi

Understanding the structure of real data is paramount in advancing modern deep-learning methodologies. Natural data such as images are believed to be composed of features organized in a hierarchical and combinatorial manner, which neural networks capture d ...

National Academy of Sciences2025

Geometric compression of invariant manifolds in neural networks

Matthieu Wyart, Mario Geiger, Leonardo Petrini, Jonas Paccolat

We study how neural networks compress uninformative input space in models where data lie in d dimensions, but the labels of which only vary within a linear manifold of dimension d(parallel to) < d. We show that for a one-hidden-layer network initialized wi ...

IOP PUBLISHING LTD2021

Does a Growing Static Length Scale Control the Glass Transition?

Matthieu Wyart

Several theories of the glass transition propose that the structural relaxation time tau(alpha) is controlled by a growing static length scale. that is determined by the free energy landscape but not by the local dynamic rules governing its exploration. We ...

American Physical Society2017

Mean-Field Description of Plastic Flow in Amorphous Solids

Matthieu Wyart

Failure and flow of amorphous materials are central to various phenomena including earthquakes and landslides. There is accumulating evidence that the yielding transition between a flowing and an arrested phase is a critical phenomenon, but the associated ...

American Physical Society2016

Armouring of a Frictional Interface by Mechanical Noise

Matthieu Wyart, Thomas Willem Jan de Geus, Elisa El Sergany

A dry frictional interface loaded in shear often displays stick–slip. The amplitude of this cycle depends on the probability that a microscopic event nucleates a rupture and on the rate at which microscopic events are triggered. The latter is determined by ...

2024

Evidence for Marginal Stability in Emulsions

Matthieu Wyart

We report the first measurements of the effect of pressure on vibrational modes in emulsions, which serve as a model for soft frictionless spheres at zero temperature. As a function of the applied pressure, we find that the density of states D(omega) exhib ...

American Physical Society2016

How Deep Neural Networks Learn Compositional Data: The Random Hierarchy Model

Matthieu Wyart, Leonardo Petrini, Alessandro Favero, Francesco Cagnetta, Umberto Maria Tomasini

Deep learning algorithms demonstrate a surprising ability to learn high-dimensional tasks from limited examples. This is commonly attributed to the depth of neural networks, enabling them to build a hierarchy of abstract, low-dimensional data representatio ...

American Physical Society2024

Nonlocal Effects Reflect the Jamming Criticality in Frictionless Granular Flows Down Inclines

Matthieu Wyart, Hugo Robin Louis Perrin

The jamming transition is accompanied by a rich phenomenology such as hysteresis or nonlocal effects that is still not well understood. Here, we experimentally investigate a model frictionless granular layer flowing down an inclined plane as a way to disen ...

AMER PHYSICAL SOC2021

Effect of particle collisions in dense suspension flows

Matthieu Wyart

We study nonlocal effects associated with particle collisions in dense suspension flows, in the context of the Affine Solvent Model, known to capture various aspects of the jamming transition. We show that an individual collision changes significantly the ...

Amer Physical Soc2016

Jamming with Tunable Roughness

Matthieu Wyart

We introduce a new model to study the effect of surface roughness on the jamming transition. By performing numerical simulations, we show that for a smooth surface, the jamming transition density and the contact number at the transition point both increase ...

AMER PHYSICAL SOC2020

On the different regimes of stochastic gradient descent

Matthieu Wyart, Antonio Sclocchi

Modern deep networks are trained with stochastic gradient descent (SGD) whose key hyperparameters are the number of data considered at each step or batch size B, and the step size or learning rate n. For small B and large n, SGD corresponds to a stochastic ...

National Academy of Sciences2024

Thermally activated flow in models of amorphous solids

Matthieu Wyart, Thomas Willem Jan de Geus, Marko Popovic, Wencheng Ji

Amorphous solids yield at a critical value Sigma(c) of the imposed stress Sigma through a dynamical phase transition. While sharp in athermal systems, the presence of thermal fluctuations leads to the rounding of the transition and thermally activated flow ...

AMER PHYSICAL SOC2021

On variational arguments for vibrational modes near jamming (vol 114, 26003, 2016)

Matthieu Wyart, Eric DeGiuli

IOP Publishing - EPL Association2016