I am a postdoctoral fellow in the Biophysics & Non-Equilibrium Statistical Mechanics group of the physics department of the Technion. There I have the opportunity to collaborate with Guy Bunin and Yariv Kafri. Before joining the Technion, I did my PhD at the Université Paris Cité under the supervision of Frédéric van Wijland. The manuscript of my thesis can be found here. Here is a short CV.

I am interested in nonequilibrium statistical physics and on the consequence of time-reversal symmetry-breaking on the phase behavior of many-body systems. My work emphasizes microscopic models, complex enough to account for a non-trivial phenomenology at the macroscopic scale yet simple enough to allow analytical progress. During my PhD, I focused on active matter and self-propelled particle systems. In active systems, the individual particles self-propel by extracting energy from the environment. This breaks the balance between dissipation and injection of energy and drives the simplest versions of such interacting particle systems away from equilibrium. Their rich macroscale behavior has stimulated the interest of physicists over the past 30 years.

Recently, I got interested in models of large ecosystems. I follow an approach pionereed by Robert May, himself inspired by the earlier treatment of Eugene Wigner on heavy nuclei, and consider models in which the interaction parameters are treated as random numbers. This approach is motivated by questions in both theoretical ecology and statistical physics. In large real-world ecosystems, it is difficult to obtain a quantitative description of the interactions between every species. However, recent analyses point to universal trends in their coarse-grained properties. Can these be understood as generic emergent properties of systems with reproduction, death and heterogeneous interactions? The models I study address this question and make concrete predictions of novel universal behavior potentially guiding future experimental work. More generally, these models offer a natural framework to investigate the consequences of non-conservative interactions and time-reversal symmetry-breaking on the large-scale properties of complex systems.

News

29/10/2023: My preprint with Frédéric van Wijland on A run-and-tumble particle around a spherical obstacle: steady-state distribution far-from-equilibrium has been accepted in J. Stat. Mech.
15/09/2023: My preprint with Guy Bunin on Many-species ecological fluctuations as a jump process from the brink of extinction is out on the arxiv.

Publications

Preprints

Thibaut Arnoulx de Pirey and Guy Bunin. Many-species ecological fluctuations as a jump process from the brink of extinction. [arxiv]

Published articles

Thibaut Arnoulx de Pirey and Frédéric van Wijland. A run-and-tumble particle around a spherical obstacle: steady-state distribution far-from-equilibrium. To appear in Journal of Statistical Mechanics (2023). [arxiv]
Thibaut Arnoulx de Pirey and Guy Bunin. Aging by Near-Extinctions in Many-Variable Interacting Populations. Physical Review Letters (2023). [Phys. Rev. Lett.] & [arxiv]
Thibaut Arnoulx de Pirey, Leticia F. Cugliandolo, Vivien Lecomte, and Frédéric van Wijland (2022). Path integrals and stochastic calculus. Advances in Physics (2022). [Adv. in Phys.] & [arxiv]
Thibaut Arnoulx de Pirey and Frédéric van Wijland. Nonlinear analog of the complexity-stability transition in random dynamical systems: a replica calculation. Journal of Physics A: Mathematical and General (2023). [J. Phys. A] & [arxiv]
Thibaut Arnoulx de Pirey, Alessandro Manacorda, Frédéric van Wijland, and Francesco Zamponi. Active matter in infinite dimensions: Fokker–planck equation and dynamical mean-field theory at low density. The Journal of Chemical Physics (2021). [J. Chem. Phys.] & [arxiv]
David Martin and Thibaut Arnoulx de Pirey. AOUP in the presence of brownian noise: a perturbative approach. Journal of Statistical Mechanics: Theory and Experiment (2021). [J. Stat. Mech.] & [arxiv]
Thibaut Arnoulx de Pirey, Gustavo Lozano, and Frédéric van Wijland. Active hard spheres in infinitely many dimensions. Physical Review Letters (2019). [Phys. Rev. Lett.] & [arxiv]
Thibaut Arnoulx de Pirey and Nicolas Yunes. Cosmological evolution and solar system consistency of massive scalar-tensor gravity. Physical Review D (2017). [Phys. Rev. D] & [arxiv]

Some online talks

About “Inclusions in momentum conserving active fluids” during the Frontiers in Statistical Physics conference, Bengaluru, December 2023. [Link]

Teaching

From 2018 to 2021, I worked as a teaching assistant in the “Frontières du Vivant” bachelor program of the Université Paris Cité. The topics covered were Newtonian mechanics, thermodynamics, geometrical optics and electronics. In the fall 2021, I was given the opportunity to be the main lecturer of the Newtonian mechanics course.

I have also worked as an oral examiner in mathematics and physics at first and second year level of preparatory class (equivalent to first and second year of bachelor in mathematics and physics) at Lycée Louis-le-Grand in Paris.