Ph.D. candidate · IPCMS · Université de Strasbourg

PierreGuichard

I compute what happens when an atom meets other matter — whether two atoms of antimatter could bind into a molecule, how a hydrogen atom crosses a single sheet of graphene as a wave, and where a magnetic moment can come from in a cage of carbon that holds no magnetic atom.

Three questions that no single experiment relates, approached with the same three instruments: matter treated as a wave, the atom taken as a projectile, and the electron density.

Publications Course notes

Interests

What I keep coming back to

Topological matter

Where a global property of a system — the shape of a cage, the winding of a phase — decides what it does, rather than any local detail. I started with Berry phases and symplectic geometry, spent an internship on the quantum Hall effect, and ended up finding magnetism in a carbon cage that contains no magnetic atom. It keeps being the same idea.

History and epistemology of science

A working conviction that how a field comes to believe something is part of the physics itself. Kuhn on scientific revolutions, and bibliometrics as a way of watching one happen from the outside.

Antimatter

Whether two antiatoms could bind into a molecule, how fast, and what an experiment would have to do to see it. Member of the GBAR collaboration at CERN.

Matter-wave interferometry

Atoms and molecules taken as waves — how far up in mass the interference survives, what destroys it, and what a diffraction pattern can be made to measure along the way.

Electronic structure

Density functional theory and its time-dependent form: what an electron density can be asked to tell you, where it stops being enough, and what the cheapest honest description is.

Chaos, noise and collective behaviour

Telling a deterministic mess from a random one, and the moment where a crowd of particles stops behaving like a sum of collisions and starts behaving like a mode.

Published

01

Carbon nitride monolayer nanosheets: astrochemical insights into the fate of interstellar hydrogen

D. Dubois, P. Guichard, R. Pasquier

Physical Chemistry Chemical Physics 28, 11292–11302 (2026)doi:10.1039/D6CP00221H
02

Record accumulation of antiprotons in a Penning–Malmberg trap and their preparation for improved production of antihydrogen beams

B. Lee, B. Kim, P. Adrich et al. (38 authors, incl. P. Guichard)

Journal of Physics G: Nuclear and Particle Physics 53, 085002 (2026)doi:10.1088/1361-6471/ae7456GBAR collaboration
03

Fast hydrogen atom diffraction through monocrystalline graphene

P. Guichard, A. Dochain, R. Marion, P. de Crombrugghe de Picquendaele, N. Lejeune, B. Hackens, P.-A. Hervieux, X. Urbain

Physical Review Letters 135, 263403 (2025)doi:10.1103/wdx6-mrvmEditors’ Suggestion

First observation of a neutral atom diffracting in transmission through a single sheet of graphene.
04

News from the GBAR experiment: improved positron accumulation in a buffer gas trap with a silicon carbide remoderator

L. Liszkay, P. Adrich, I. Belosevic et al. (49 authors, incl. P. Guichard)

Journal of Physics: Conference Series 3149, 012002 (2025)doi:10.1088/1742-6596/3149/1/012002GBAR collaboration

All publications

“Seulement on n’est jamais sûr d’être assez fort, puisqu’on n’a pas de système, on n’a que des lignes et des mouvements.”

Deleuze & Guattari · Mille plateaux · 1980