YIC 2025: schedule and abstracts

13h00 

Opening of the conference

13h05 

13h15

Corentin ARVOR Path integrals: from quantum mechanics to numerical simulations.

We explore the application of the Path Integral formalism from Quantum Mechanics to computer simulations through the Statistical Physics of Polymers. We begin with Feynman’s reformulation of Quantum Mechanics, he introduces the concept of path integrals as a summation over all possible trajectories of a particle. Through a Wick rotation, this formalism is translated to Statistical Mechanics. We then analyze some polymer models and their statistical properties using Path Integrals. Finally, we incorporate our knowledge in computational simulation to create random polymer chains, evaluated using the Metropolis criterion. We introduce several physical potentials to study their influence on polymer behavior.

13h35

Loris DELAFOSSE Path integrals and topology

Path integrals are a powerful and insightful approach to the quantisation of classical theories. Unfortunately, it is very difficult to give them rigorous mathematical meaning in many cases. In this presentation, we examine on a few examples how topology sheds light on the nature of the quantisation procedure. We first review the classical notion of topological charge, which we use to explain the (topological) quantisation of the electric and magnetic charges. Secondly, we discuss the quantisation of the elecromagnetic potential through the BRST procedure, and finally we describe the relationship between topology and fermionic statistics.

13h55

Theo VUILLEMARD  Quantum Field Theory I

This talk introduces the canonical quantization of real and complex scalar fields in the framework of quantum field theory. Beginning with the classical action and the Lagrangian formulation, the session explains how the Klein-Gordon equation is derived and how its plane wave solutions provide the basis for quantization. The field is then promoted to an operator, interpreted as a collection of independent harmonic oscillators, allowing the definition of creation and annihilation operators and the quantum state space. The presentation also details the calculation and role of the Feynman propagator, a central tool for describing particle propagation and interactions. Finally, the introduction of λϕ⁴ interactions leads to an overview of perturbation theory and the diagrammatic approach using Feynman diagrams, laying the foundation for understanding more advanced quantum field theory concepts.

14h15

Axel BOUCHE Quantum Field Theory II: Renormalisation

This talk is an introduction to the principles of renormalisation through the example of the scalar field. We will first demonstrate the necessity of renormalisation. Then we will introduce the concept of regularisation, briefly illustrate it by examples tied to dimensional regularisation, which will allow us to make sense of the UV divergences found in the Φ^4 theory. After showing that adding counter-terms to the original Lagrangian can solve the issue of UV divergences, we will conclude that a clever choice of parameters in the Lagrangian can lead to a finite theory and also discuss various renormalisation schemes.

14h35

Coffee break and Poster session

15h00

Romain KRIEGER Study of stellar currents in a non-axisymmetric galactic potential

We are studying the dynamics of a stellar stream originating from the globular cluster Palomar 5, under the gravitational effect of a non-axisymmetric galactic potential. We aim to investigate the influence of the galactic bar on the evolution of Palomar 5's orbit and on the formation of its stream resulting from tidal effects induced by the Milky Way. To do this, we used Agama software to model the galactic potential, integrating a rigid rotating bar and Palomar 5's orbit from its initial conditions. This allows us to observe the influence of the bar on the morphology and orbit of the stream in cases with and without a modeled bar, particularly by studying the impact of its angular velocity. The results show that the presence of a galactic bar can induce distortions, such as asymmetries and deviations, in the stream structure, linked to the interaction between Palomar 5's orbit and the bar's rotation. This work constitutes a first step toward a more comprehensive modeling approach, taking into account more realistic clusters and direct comparison with observational data.

15h20

Maëlys CHAMARY Determination of the Structure of Milky Way Globular Clusters from Pristine and Gaia Surveys

The goal is to determine the structure of globular clusters in the Milky Way using the Pristine and Gaia surveys. These very old clusters are subject to galactic tidal effects that can tear their stars apart to form stellar streams. The initial objective was to isolate the member stars of the M5, M15 and M92 clusters based on their metallicity and proper motion properties. To do this, several filtering methods (‘cuts’) were developed: isochronal, metallicity, uncertainty and proper motion. The results show that the stars in the clusters have low metallicity and that their density decreases with distance from the centre. In a second step, analysis of the dispersion of the stars enabled the identification of stellar streams. This work paves the way for more accurate modelling of stellar structures and a better understanding of the dynamic evolution of clusters. 

15h40

Elodie HARLE  Ultrafast imaging of molecular dynamics in helium nanodroplets

In this talk, I will present recent work from Aarhus University (Denmark), reported at the ECAMP conference in July 2025 in Innsbruck. The study focuses on sodium ions in helium nanodroplets, and more specifically on the very first steps of the solvation process. Using time-resolved techniques, the experiment provides the first direct observation of how successive helium atoms attach in real time to an instantly created Na⁺ ion at the droplet surface. From this, both the binding rate and the energy dissipated from the local region around the ion can be extracted. I will introduce the methods used to achieve these measurements and discuss how the results provide new benchmarks for theoretical models of ion solvation.

16h00

Romain RIEDER Feschbach resonance and Pauli engine

The Pauli exclusion principle is at the heart of quantum statistics, giving rise to a quantum pressure that can be harnessed as a Pauli engine. Ultracold Fermi gases provide a unique platform to explore this concept, where quantum degeneracy and interactions play a central role. Using a Feshbach resonance, the effective interactions between fermionic atoms such as 6^{6}6Li can be tuned, allowing a smooth crossover from a molecular Bose–Einstein condensate to a strongly correlated Fermi sea. This controllability highlights how Pauli’s principle, combined with interaction tuning, enables novel routes to quantum thermodynamic engines and exotic phases of matter.