Rencontres Jeunes Physicien.ne.s 2026

vendredi 24 avr. 2026, 09:00 → 20:40 Europe/Paris

Amphithéâtre principal (La Doua)

Arthur ALLEN (ILM), Ines BENTARA, Feyza BEZIANE (ILM), Chloe BRAUX, Lilou DUPLANTIER, Florencia JUAREZ SABORIO, Tatiana LE BELLEC (IP2I), Max MARROT, Joseph MOREAU, Leo ZIMMERMANN

Our 4th annual meeting for early-stage physicists to present your work in a safe, friendly and chill space! 

A conference for PhD students & Postdocs organized by PhD students and postdocs members of the Youth Section of the French Physics Society (Société Française de Physique)! The main goal of this meeting is to create a link between early-stage researchers in different laboratories from Lyon and Saint-Etienne and for everyone to get a chance to present their work in a fun manner so that we learn more about the wide range of physics, as well as getting to know more physicists in your area.

Participants are encouraged to deliver a  presentation followed by a Q&A session. Coffee breaks and lunch will be provided to all participants. Additionally, a social event with free drinks and food will be organized at the end of the day.

To acknowledge outstanding contributions, exciting prizes will be awarded to participants. This recognition serves as an encouragement for the exceptional work conducted by the speakers.

The RJP talk opportunities are mainly reserved for early-career researchers, particularly 1st and 2nd-year PhD students, and the organizing committee is looking forward to receiving your contribution!

Just like in 2025, we now have a poster session! All accepted posters will be printed by our team at no cost to you, and we encourage presenters to reuse their posters at future conferences and events.

09:00 Morning Announcements : Welcome and Opening

Session 1

Président de session: Inès Bentara

1 Detector R&D for Future High-Energy Colliders: Instrumentation and Deep Learning Developments for the Timing-SDHCAL

As a brief introduction, the Semi Digital Hadronic Calorimeter (SDHCAL) is a concept of a gaseous hadronic calorimeter based on Resistive Plate Chamber (RPC) technology, originally designed for the future linear collider ILC. In the context of future circular colliders such as FCC and CEPC, an upgraded version - the Timing SDHCAL (T-SDHCAL) - is currently under development. It incorporates precise timing capabilities provided by Multi-Gap RPC (MRPC) technology.

During this talk, I will give an overview of my PhD research. The first part focuses on the design, construction, and characterization of several 50cm × 30cm MRPC prototypes. The second part explores the use of deep learning techniques to improve the reconstruction of the energy of incoming particles.

Orateur: William VAGINAY (CNRS - IP2I)

2 Introduction to Higgs physics: search for Higgs pair production with CMS

Since the discovery of the Higgs boson in 2012, the main goal of the CMS collaboration has been to characterize the Higgs boson and measure its potential. One of the most important characteristics to measure is the Higgs boson self-coupling $\lambda$: this fundamental parameter is notably responsible for the breaking of the electroweak symmetry during the Big Bang and possibly of the predominance of matter over antimatter. Its value is predicted by the Standard Model: $\lambda$ = 0.13. Any deviation from this prediction would be synonymous with physics beyond the Standard Model.
Production of Higgs boson pairs (HH) is sensitive to probe the structure of the Higgs potential through the Higgs boson self-coupling, and to search for beyond the standard model heavy particles that couple to HH.
In this talk, we will introduce Higgs physics and the aforementioned challenges related to its study since its discovery in 2012; and we will present in a general manner the goal of the thesis, which is the search for double Higgs production decaying into 2 photons and 2 b quarks, using the Run 3 data from CMS in order to study its self-coupling $\lambda$.

Orateur: Eva DIDIER-ESTEVE (IP2I)

eva_didieresteve.pdf

3 Dualities and correspondances in supersymmetric gauge theories

I will summarize and give hints to exact results in quantum field theory, and algebraic/geometric intepretation of correspondances between seemingly very different quantum theories.

Orateur: Timothé ALEZRAA (IP2I, Lyon)

RJP_ALEZRAA.pdf

4 Preliminary measurement of the germanium ionisation yield and first studies of the new silicon crystal detectors of the Ricochet experiment

Coherent elastic neutrino nucleus scattering (CEvNS) was first measured experimentally by the COHERENT experiment in 2017 and is currently being studied by many experiments all around the world. In this context, the Ricochet international collaboration aims to detect the CEvNS process in order to search for new physics. The detectors used are germanium crystals operated at cryogenic temperatures, which can simultaneously readout the ionization and heat energies resulting from particle interactions occurring in the crystal.This dual measurement allows both particle identification, by discriminating between electronic and nuclear recoils, and determination of the recoil energy of the interactions. This presentation focuses on a preliminary study dedicated to measure the ionization yield of nuclear recoils in germanium detectors at the keV energy scale, based on the first commissioning data from the Ricochet experiment. Furthermore, as the Ricochet experiment is planning to use silicon as a new crystal material, this presentation is also covering the first hardware developments and preliminary performance analysis of the silicon detectors.

Orateur: Tatiana LE BELLEC (IP2I)

RJP_pres.pdf

5 The RICOCHET experiment : status and prospects

The RICOCHET experiment is operated by an international collaboration that aims to observe coherent elastic neutrino-nucleus scattering (CEνNS) to reveal deviations in the electroweak sector from the Standard Model of particle physics. The setup is situated 8.8m from the core of research reactor at the Institut Laue-Langevin (ILL, Grenoble, France). The detection principle consists in germanium-based cryogenic bolometers, called CryoCube, which can identify particles interactions in the crystal based on a dual measurement of phonon and ionization signals, allowing discrimination between electronic and nuclear recoils. RICOCHET began its first science phase in July 2025 with 18 detectors installed, and is foreseen to complete at the end of 2026. This talk will present the overall technology employed by RICOCHET, as well as results from commissioning runs and prospects.

Orateur: Romain Faure (IP2I MANOIR)

RJP - Romain Faure.pdf

Posters: Coffee Break, Poster Session and Art Exhibition

6 A Traveling-Wave based Ion-Mobility device for isomers selection in InfraRed Multiple Photon Dissociation analysis

In nature, molecular ions with the same mass and charge can exist with various structures. These isomers exhibit different physical or chemical properties. For a better understanding of light-induced processes on molecules, one of the actual challenges is to couple structural analysis of molecular ions with light matter interaction studies. To probe the structure of gas-phase molecular ions, especially for complex and flexible systems, ion mobility spectrometry (IMS) combined with mass spectrometry (MS) and infrared multiple photon dissociation (IRMPD) provides a powerful approach [1,2].

In the DYNAMO group, molecular ions in the gas phase are studied with interests in both fundamental and application aspects by using state of the art table-top light sources technologies (from mid-infrared to extreme ultraviolet) coupled to electrospray Ionization source (ESI) and mass spectrometers. A novel IMS experimental apparatus using ultrahigh-resolution traveling-wave SLIM (Structures for lossless ion manipulation) technology [3] is currently under construction. This IMS system will be coupled to an ESI-MS-IRMPD experimental setup for the analysis of carbohydrates and complex molecular assemblies.

In ESI-SLIM-MS-IRMPD experiments, molecular ions are generated by ESI and separated based on their structures using the SLIM device. Selected isomers are then trapped, mass-isolated, and irradiated with a tunable IR laser to obtain IRMPD spectra, which provide structural fingerprints of the selected ions (Figure 1).
The ESI-IMS device with preliminary results will be presented.

References
[1] Schindler, B et al. FAIMS-MS-IR spectroscopy workflow: a multidimensional platform for the analysis of molecular isoforms. Int. J. Ion Mobil. Spec. 20, 119–124 (2017).
[2] Ben Faleh, A et al. Combining ultrahigh-resolution ion-mobility spectrometry with cryogenic infrared spectroscopy for the analysis of glycan mixtures. Anal. Chem. 91, 4876–4882 (2019)
[3] Ibrahim, YM et al. New frontiers for mass spectrometry based upon structures for lossless ion manipulations. Analyst 142, 1010-1021 (2017)

Orateur: PengFei Xu (Université Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69100, Villeurbanne, France)

Figure1.png

7 CO2 Reduction by bio-inspired up-converting photonic structures

In order to reduce the effect of global warming, the decarbonation of the industry via CO2 capture and valorisation became a well studied topic. In this poster, I shall present the work I will tackle during my PhD, on up-converting photonic crystals for CO2 reduction reaction applications. This poster is a global overview of the physics and chemistry behind, objectives and current work related to my PhD.

Orateur: Eryk Kupiec (INL)

Poster RJP vfin (2).pdf

8 Experimental study of the optical response of gold nanobipyramids used as photoelectrochemical electrodes

Gold nanoparticles are a versatile tool for probing and monitoring their local environment. On the one hand, they exhibit optical extinction dominated by Localised Surface Plasmon Resonance (LSPR) whose spectral maxima and width are sensitive to their local environment. On the other hand, selective electrochemical reactions can be driven on electrodes with gold nanoparticles deposited on their surface, allowing, for example, the detection of heavy metal pollutants in water.
In this work, we have developed a setup combining Spatial Modulation Spectroscopy (SMS), which allows optical measurements on single nano-objects, and voltamperometric measurements. Synthesised Au bipyramids (100 nm in length) have been grafted by silanisation onto an ITO-coated glass substrate. This sample is used as the working electrode in a 0.1 M KNO3 electrolyte (counter electrode: Pt wire) in a 2 cm thick glass cell. The cell is mounted on an open vibrating piezoelectric stage and inserted into a home-built confocal microscope. Light from a collimated white lamp is focused onto the sample and collected in a spectrophotometer (wavelength range: 450-950 nm). Signals from the spectrophotometer are processed with a lock-in amplifier system to extract the extinction signal of individual nanoparticles. SEM images of the samples were also taken.
We performed potential cycling and recorded the optical response of Au bipyramids. The plasmonic responses to the stepwise applied potential show a redshift up to 40 nm and a decrease in intensity as the potential is increased from 0 to 1.4 V/Ag-AgCl (KCL sat.), which is consistent with the formation of a gold oxide layer on the surface of the nanoparticle. Analysis of the relationship between the potentials at which the gold oxidation reaction occurs and the associated change in the spectral characteristics of individual gold nanoparticles could enable the detection of deposited metallic contaminants.

Orateur: M. Youn NOH (Institut Lumière Matière (iLM))

Abstract MNO 2026 Youn NOH.docx

9 Formation et migration d’instabilités à la surface libre d’un lit granulaire immergé

Dans cette étude expérimentale, on s’intéresse à l’injection localisée d’eau dans un milieu granulaire immergé (système diphasique). L’état initial est obtenu par sédimentation de grains dans une cellule de Hele-Shaw verticale. De l’eau colorée est ensuite injectée à débit constant en bas de la cellule, au centre, par une buse cylindrique. Une caméra et un panneau lumineux permettent une visualisation directe des mouvements du fluide et, éventuellement, des grains. La couche de grains, dont on fait varier la hauteur, est constituée d’un mélange bidisperse de billes de verre sphériques de diamètres respectifs de l’ordre de 160 et 40 micromètres. Dans une certaine gamme de paramètres expérimentaux, on observe le développement d’instabilités quasi-périodiques à la surface libre du lit granulaire immergé, qui migrent à vitesse constante vers le centre de la cellule.

Orateur: Camille Porceillon (Laboratoire de Physique (ENS de Lyon) & Géosciences Montpellier)

10 Influence of Mantle Rheology on Plume Dynamics, Periodicities and Morphologies

Many hotspots worldwide display evidence of fluctuating magmatic activities that may be linked to time-dependent variations in melt production within mantle plumes. These periodicities are observed globally on Earth, ranging from 1 Myr to 20 Myr [Morrow and Mittelstaedt, 2021 ; Sokolov et al., 2025]. Remarkably, the Réunion hotspot exhibits short magmatic pulsations with a periodicity of ~400 kyr [Famin et al., in rev.]. Given the ~230 km separation between La Réunion and Mauritius, the synchronous short-period pulsations observed at the Réunion hotspot imply that they originate from deeper plume dynamics.

Understanding the physical controls behind these pulsations could establish links between mantle convection, plume dynamics, and surface volcanism. Previous studies suggest that plume behavior is sensitive to mantle rheology. Plume pulsations with periods of ~1-10 Myr have indeed been reported in numerical experiments and can stem from thermochemical instabilities due to the interaction of plumes with small-scale convection in the asthenosphere [Ballmer et al., 2009], thermal instabilities in sufficiently vigorous convection (Rayleigh number > 5×10⁶), buoyancy changes due to mineralogical phase transitions [Trubitsyn and Evseev, 2018], horizontal shearing caused by plate motions over an asthenosphere dominated by dislocation creep, leading to unstable tilted plume conduits [Neuharth and Mittelstaedt, 2023].

Here, we seek to investigate how mantle rheology can favour short-period pulses of plume activity and aim to identify the core physical mechanisms that control plume dynamics. We thus run 3D regional convection models in spherical cap geometry with plate-like behavior (viscoplastic rheology) at the surface using the StagYY code [Tackley, 2000]. We developed an automated algorithm to detect and track plumes in space and time, by defining plumes as the highest percentiles of the upwards vertical advective heat transport . The morphology and dynamics of plumes are then quantified using various parameters such as the buoyancy flux, heat flux, angle of inclination, along with their associated uncertainties. Our study explores the effects of surface yield stress (ranging 10-100 MPa), radiogenic heat production (3-15 pW/kg), a 30 to 100 fold viscosity jump at the transition zone, and of compressibility and phase transitions (especially the ringwoodite/bridgmanite solid-solid phase transition at ~660 km depth that works as an accelerator of upwellings plumes and thus favors dynamic instabilities [Faccenda and Dal ZIlio 2016]) on plume dynamics as well as on plate tectonics. We aim to understand how these parameters control the generation of periodic activity and short-period term plume pulses and ultimately to estimate melt production variations at the surface in order to compare it with geological observations of magmatic products at the Réunion hotspot. Preliminary results indicate that surface yield stress and radiogenic heat production primarily affect plate tectonics, whereas a viscosity jump across the transition zone promotes periodic (~2 Myr) plume behavior.

Orateur: Alexandre Koessler

11 Mechanical Behaviour of Confined Ferromagnetic Granular Media

The pressure at the bottom of a container filled with granular material saturates [1], as the silo walls can support part of the grains' weight due to frictional interactions, a phenomenon known as the “Janssen Effect.”

We investigate this effect using ferromagnetic particles: when exposed to a magnetic field, these particles acquire a magnetic moment, leading to anisotropic magnetic interactions. We develop different experimental setups and Discrete Element Method (DEM) simulations [2], in both 3D and 2D.

We demonstrated recently that applying a magnetic field aligned with the granular column results in an even greater reduction of the pressure at the bottom of the container [3] compared to the classical Janssen Effect. Strikingly, beyond a critical magnetic field or a critical mass of grains, the apparent weight of the column can be completely canceled, rendering the column undetectable on the scale!

We focus on the approach of the “invisibility” threshold, examining the impact of the magnetic field intensity and the initial mass of grains. We also studied the influence of the proportion of ferromagnetic grains within the column: the pressure at the bottom of the column decreases only when the fraction of magnetic grains exceeds a threshold corresponding to the percolation of magnetic clusters [4].

[1] Janssen, H. A. Investigations of pressure of grain in silo. Vereins Eutscher Ingenieure Zeitschrift 1045-1049 (1895).

[2] J. Sautel, C.E. Lecomte, N. Taberlet, Particle size segregation in two-dimensional circular granular aggregates. Physical Review E, 103(2), 022901 (2021).

[3] L. Thorens, K.J. Måløy, M. Bourgoin, S. Santucci, Magnetic Janssen effect, Nature Comm., 12, 2486 (2021).

[4] L. Thorens, S. Rodriguez, N. Taberlet, M. Bourgoin, K.J. Måløy, S. Santucci, Hybrid Magnetic Janssen Effect Arising from Percolating Ferromagnetic Grain Networks, submitted 2026

Orateur: Solenn Rodriguez (Laboratoire de physique de l'ENS de Lyon)

12 Realistic simulations for cosmology with type Ia Supernovae (SNe Ia).

SNe Ia are at the center of the actual tensions on H0 and w, parameters characterising the expansion of the Universe. Controlling surveys cross-calibration, selection functions and SNe Ia variability is important to avoid systematic biases in cosmological inference from SNe Ia. Realistic simulations are essential to address these systematics, but existing tools remain limited in their ability to capture the full complexity of SNe Ia populations and survey effects. I will introduce the context of my PhD by presenting the skysurvey framework, a simulation code made to simulate transients, like SNe Ia, as observed by any survey. I'll compare its predictions with the DR2 from the ZTF survey, and dicuss the future developments of this code so that we can simulate selection effects, SNe Ia population properties and their correlations with host-galaxy environments. This kind of realistic simulations can, in turn, be used to assess the accuracy of existing inference model.

Orateur: Luna Dellazzeri (IP2I)

13 Simulation-Based Inference (SBI) for cosmology with type Ia Supernovae (SNe Ia).

Systematic uncertainties associated to calibration, selection function and astrophysical effects are dominating the error budget of SN Ia cosmology. Correction methods applied to account for these systematics, and especially for the complex combination of selection function and astrophysical variability, are questionable, particularly given the current H0 and Lambda tensions for which SN Ia data are central.

Recently, the ZTF survey has produced a volume-limited sample of more than a thousand of SNe Ia, allowing us to directly probe the distribution of SNe Ia parameters without being affected by selection effects. We use the skysurvey simulator to simulate the ZTF volume limited dataset in order to train a neural network that infers input simulation parameters.

This novel inference method, called SBI, is a promising avenue to solve the complex problem of cosmological inference with SNe Ia data, and thus to accurately derive H0, w0 and wa. I will review the status of this ongoing activity.

Orateur: Adam Trigui (IP2I)

14 Suface functionalisation of nanoplatelets for detection of biological nanoobjects in water

Detecting biological objects, such as viruses or proteins, through their mechanical vibrations is possible but remains challenging due to their structural complexity and weak signals1. To overcome these limitations, we propose an indirect detection approach by coupling such biological objects to colloidal nanocrystals acting as mechanical nanoresonators. Here we use CdS nanoplatelets (NPLs), which are 2D semiconducting nanocrystals with thickness controlled at the atomic scale. Thanks to their structure, these nanocrystals exhibit a well-defined low-frequency vibrational mode and sharp optical properties, highly sensitive to surface chemistry modifications. Indeed, pristine CdS NPLs, covered with a dense carboxylate ligands layer, can be exchanged to thiolate or phosphonate ligands, leading to a decrease in excitonic energy2. In addition, changing the mass of ligands shifts the low-frequency Raman vibrational modes of NPLs due to the mass-load effect3.
In this work, CdS nanoplatelets are functionalised with mercaptopropionic acid (MPA), mercaptoundecanoic acid (MUA) or dihydrolipoic acid (DHLA) and subsequently transferred into water to obtain colloidally stable solutions with reactive surfaces – carboxylates. They can be subsequently coupled with a biological nanoobject via EDC coupling which is a common coupling process in biochemistry.
We use a combination of low-frequency Raman spectroscopy, FTIR, optical absorption spectroscopy and transmission electron microscopy (TEM) to study the completion of the ligand exchange. The results indicate a ligand surface coverage dependent of the ligand used, and validate the use of low-frequency Raman spectroscopy to study surface ligands in water dispersible NPLs.
These results demonstrate the feasibility of surface functionalisation of CdS nanoplatelets for further coupling with biological nanoobjects and represent a first step toward indirect vibrational detection of biomolecules.

Orateur: Maria Bandurist (ILM)

Session 2

Président de session: Léo Zimmermann (Onde Gravitationelle, Cosmologie)

15 Dynamics of the oxygen driven micro-phase separation of social amoebas

When reaching high densities, Dictyostelium discoideum (Dd) cells find themselves lacking oxygen and spontaneously self-organize into dynamic, size-stable aggregates. The aggregates coexist with a dispersed cellular phase resulting in an original example of micro phase separation of living cells (Carrere et al, Nat Comm, 2023). This form of collective behavior is distinct from the classical cAMP-mediated aggregation associated with starvation. We have previously shown that the aggregates’ typical size emerges from a balance between two competing interactions: a short-range adhesive attraction, and an effective long-range repulsion driven by self-generated oxygen gradients and the aerotactic ability of the involved cells. As such, this phase separation is primarily driven by oxygen availability with no signature of two different cell populations. However, unlike in other instances of micro phase separation in inert systems, the cellular aggregates are highly motile, display persistent trajectories and dynamic interactions over several days. Using mean-squared-displacement analysis, we quantify their dynamics and uncover a clear size dependence: larger aggregates move more persistently and explore broader regions than smaller ones. This behavior suggests a high degree of collective coordination within aggregates. Preliminary simulations based on the Cellular Potts Model support this cooperative scenario and reproduce qualitative features of the experimental observations. To decipher the mechanisms of this cooperation, we use fluorescence imaging to track individual cells and quantify the exchange fluxes of cells between both phases. We expect to uncover from these experiments how cells behave inside an aggregate, and obtain a clearer picture of the mechanical motion of the whole aggregate as a collective. All these observations underline the potential of this unique phenomenon, which may constitute a new model system for active matter.

Orateur: Lucas BOISTAY (ILM)

Presentation.pdf

16 Reactions in a Leidenfrost film

We investigate Leidenfrost state in a particular situation, with a cylindrical micrometric wire heated in an ambient temperature liquid pool. When the thermal power supplied to the wire is large enough, the Leidenfrost transition occurs, manifested by a large increase of the wire temperature.

Orateur: Lorena Victoria-García (CNRS, ILM)

Abstract RJP Lorena V-G.pdf

17 Tailoring Attosecond Charge Migration in Native Molecular Ions

Attosecond XUV pulses provide a powerful tool to trigger pure electron dynamics in molecules, such as the so-called cahrge migration [1,2]. While charge migration has been extensively studied in neutral molecules following ionization [3], its counterpart in pre-charged systems (molecular ions) remains largely unexplored. Such systems are ubiquitous in chemical and biochemical environments, and understanding their intrinsic electron dynamics offers new opportunities to control and probe electron correlation effects in realistic settings.

In this work, we investigate correlation-driven charge migration in molecular ions using non-Dyson algebraic diagrammatic construction [4] combined with multi-electronic wave-packet propagation [5]. We consider a series of systems with different native charges by examining protonated and deprotonated derivatives of molecules exhibiting strong outer-valence electron correlation (hole mixing).

Our results demonstrate that protonation and deprotonation affect outer-valence electronic structure and dynamics in markedly different ways. Protonation suppresses correlated dynamics by strongly altering the preferred ionization sites, whereas deprotonation reduces correlation strength while significantly accelerating charge migration. In both cases, these effects are rationalized in terms of the spatial distribution of the excess charge prior to ionization. Furthermore, comparison across different molecules suggests that systems with similar structures (geometry and functional groups) respond in a consistent manner to the added charge. These findings highlight how molecular charge state can be used to tailor electron correlation and ultrafast charge dynamics, opening new perspectives for the design of systems with controlled electronic behavior.

References:
[1] Cederbaum L. S., and Zobeley J., Chem. Phys. Lett. , Vol. 307, No. 3-4 (1999)
[2] Kuleff A. I., and Cederbaum, Lorenz S., J. Phys. B: At. Mol. Opt. Phys. , Vol. 47, No. 12 (2014)
[3] Calegari F. et al, J. Phys. B: At. Mol. Opt. Phys. , Vol. 49, No. 14 (2016)
[4] Schirmer J., Trofimov A. B., and Stelter G., J. Chem. Phys. , Vol. 109, No. 12 (1998)
[5] Kuleff A. I., Breidbach J., and Cederbaum L. S., J. Chem. Phys. , Vol. 123, No. 4 (2005)

Orateur: Evan MUNARO LANGLOYS (iLM)

main_compressed.pdf

18 Electrical Property Tuning in Self-Healing Polymeric Films via Controlled Silver Nanoparticle Deposition

Nanocomposites with controllable functional properties are increasingly being investigated for soft electronics, where precise control over electrical behavior is essential. In particular, polymeric thin films doped with metallic nanoparticles are attractive for a wide range of applications, as they combine softness, biocompatibility, and tunable electrical properties that can be adjusted through well-controlled fabrication processes. In this context, PEI/PAA layer-by-layer thin films are of particular interest due to their self-healing ability, and their electrical properties can be effectively modified through the incorporation of metallic nanoparticles while preserving their structural and mechanical characteristics. Surfactant-free silver nanoparticles (AgNPs) that are physically synthesized are employed to isolate NP-polymer interactions without ligand effects.

Conventionally, nanoparticle deposition is monitored by current measurements during deposition, which only allow detection once the percolation threshold is reached. As an alternative approach, in-situ impedance spectroscopy is employed here as a sensitive characterization technique to monitor nanoparticle deposition and to control the amount of material deposited on the substrate. Unlike current-based measurements, this method enables monitoring from the earliest stages of deposition, both before and after the percolation threshold [1].

In this study, AgNPs are produced in the gas phase, guided by electrostatic lenses through vacuum chambers, and then deposited onto polymer-coated interdigitated electrodes. While size and composition of the nanoparticles can be well controlled, achieving reliable and reproducible control over particle density and spatial distribution remains a challenge.

This investigation focuses on the influence of nanoparticle incorporation on the electrical response of the polymer film, especially concerning density and spatial dispersion. In-situ impedance spectroscopy is employed to monitor the deposition process in real time, while post-deposition electrical transport measurements are performed to assess how deposition conditions affect the functional properties of the films. Optical characterization of the plasmonic response is also carried out after deposition, providing a sensitive probe of nanoparticle interactions with the surrounding environment and with neighboring nanoparticles. Together, these characterization approaches enable a systematic exploration of nanoparticle-polymer nanocomposites, aiming to improve deposition control and better understand how nanoparticle–polymer interactions influence the electrical properties.

[1] Hensel, Rafael C., et al. Applied Surface Science 544 (2021): 148806.

Orateur: Shirley Hossack (ILM)

shirley_hossack_rjp.pdf

12:05 Lunch Break

Session 3

Président de session: ARTHUR ALLEN (ILM)

19 Electrically Injected Tamm Laser Diodes

We present the realization of a new type of laser diode based on surface-confined Tamm plasmon modes, offering an innovative approach for the design of optoelectronic sources that combine high optical performance with technological flexibility. Tamm plasmon modes are electromagnetic modes localized at the interface between a distributed Bragg reflector (DBR) and a metallic layer [1], merging key features of optical cavity modes and surface plasmons. In this approach, optical confinement is achieved through the lateral structuring of the metallic layer [2], which enables both efficient mode confinement and the realization of complex laser source geometries [3]. Importantly, the Tamm laser mode can be engineered and shaped without modifying the underlying DBR, providing additional freedom in device design and fabrication.

[1] M. Kaliteevski, et al., Phys. Rev. B, Volume 76, Pages 16, (2007),
[2] C. Symonds, G. Lheureux, J.P. Hugonin, J.J. Greffet, J. Laverdant, G. Brucoli, A. Lemaitre, P. Senellart and J. Bellessa, Nano Lett. 13, 3179 (2013).
[3] G. Lheureux, S. Azzini, C. Symonds, P. Senellart, A. Lemaitre, C. Sauvan, JP. Hugonin, JJ. Greffet and J. Bellessa, ACS Photonics 2, 842 (2015).

Orateur: MAEL LAUPRETRE

Maël_LAUPRETRE_RJP.pdf

20 Theory of transport of bacteria and statistical properties of the run-and-rotate for adherent cells

I'm going to present my work on the theory of the transport of bacteria and the analytical work I've done during my M2 internship on the statistical properties of the run-and-rotate for adherent cells that I'm still studying through simulations.

Orateur: Feyza BEZIANE (ILM)

RJP.pdf

21 Hexagonal SiGe alloy on Si substrate for Laser

Silicon is considered the backbone of the modern telecommunications industry; however, it cannot be used directly as an efficient light source due to its indirect bandgap [1]. Recent studies have shown that Si/SiGe alloys can potentially exhibit direct-bandgap behaviour when their crystal structure is transformed from the conventional cubic phase to the hexagonal phase [2]. This development opens exciting prospects for the realization of silicon-compatible light emitters and lasers, which are highly desirable for future integrated optoelectronic technologies and high-speed data transfer.
In this project, we aim to realize hexagonal SiGe (Hex-SiGe) through the epitaxial growth of III-V nanowires, which act as crystal templates, followed by the growth of a hex-SiGe shell using the crystal phase transfer method. A major objective of the work is to investigate how quantum confinement, strain, and doping influence the optical properties of the alloy, with the goal of tuning its bandgap toward the telecommunication wavelength range (1.2 to 1.6 μm). These effects are particularly important because hex-SiGe may revert to indirect-bandgap behaviour at higher Si compositions (typically for Si ≥ 35%) [2], making band structure engineering a key challenge.
In addition to material synthesis, the project also aims to explore the morphological design of nanowires so that they can function as optical cavities for laser operation, for example through suitable etching and geometry control. The produced nanowires will be investigated using a combination of structural, morphological, optical, and electronic characterization techniques.

1. Noskov. (2025). arXiv preprint arXiv:2507.19001.
2. Fadaly et al. Nature 580, 205 (2020)

Orateur: Aamir Ejaz (INL)

Aamir Ejaz-Abstract for RJPs oral presentation.odt

Aamir Ejaz- Presentation.odp

22 "Exploring early galaxy formation with JWST and SPHINX"

Since the launch of the James Webb Space Telescope, observations of the high-redshift universe have opened a new window onto the formation of the first galaxies. These early galaxies appear to undergo bursty star formation, which strongly influences their morphology. However, many large-volume cosmological simulations fail to reproduce these features, highlighting the need to better resolve stellar feedback and star formation. To investigate the origin of these discrepancies, we generate mock observations from SPHINX, a high-resolution cosmological simulation of galaxy formation and ionization in the early universe. By comparing simulated and observed galaxy properties, we explore how star formation shapes galaxy morphology in the first billion years after the Big Bang.

Orateur: Julia Shouse (CRAL)

julia_shouse.pdf

14:35 Quizz Time!

Posters: Coffee Break, Poster Session and Art Exhibition

Session 4

Président de session: Max Marrot

23 Light scattering at the service of art

I can present how an everyday life phenomenon has been used by pierre soulage in order to create the conques glasses

Orateur: Simon Milcent (ILM)

RJP 2026 Simon Milcent.pdf

24 HDBank-2: Exploring Parallelization and Normalizing Flow for Faster Hybrid Template Placement

Template banks are at the core of the modeled GW search pipelines in the LVK collaboration. The production of these banks can follow a geometrical, stochastic, or hybrid approach. Here we present a modified version of HdBank, by S.Roy et al.(1), a hybrid method that stochastically generates a set of points and then uses them as input for a geometrical algorithm. The modified version is then tested against a benchmark bank inspired by the Virtual Template bank used by the MBTA pipeline during the O4a run.

Orateur: Mattia Panzeri

Mattia_Panzeri.pdf

25 Enhancing MBTA Efficiency and Template Banks Generation for Sub-Solar-Mass Black Hole Searches

The first direct observation of gravitational waves (GW) in 2015 by the LIGO/Virgo/Kagra (LVK) collaboration opened a new era of astronomy. The GW group at IP2I in Lyon contributes to both the analysis of interferometers data and the characterization of the VIRGO detector. Most gravitationalwave online search pipelines rely on matched filtering (MF), a method which compares the data to a large set of theoretical waveforms, called templates. The Multi-Band Template Analysis (MBTA) is one of those MF-based pipelines. It filters data across several frequency bands in parallel, thus cutting down the computational overhead induced by MF.This algorithm, on the other hand, relies on more complex sets of template banks, covering the phase space over different frequency bands. My work focuses on simplifying and accelerating template bank production for MBTA, and on exploring strategies to improve MBTA’s efficiency in detecting sub-solar-mass black hole binaries.

Orateur: Gaspard Joubert

gaspard_joubert.pdf

26 Quantification of the spatial overlap of two-beams for pump-probe studies

Pump–probe experiments with focused laser pulses are nowadays widely used in non-linear physics and time-resolved science. In such experiments, the signal depends on the quality of the beams spatial overlap. Here, we propose a simple method to characterize the beams around their focus in a single shot basis. With two beams, the device performs a snapshot of their (x-y-z)-focus that quantify the overlap quality.
The usual solution to characterize a beam around its focus consists in scanning the position of a camera around its focal point. The scanning system is usually a problem in terms of alignment, space requirement, and prevent single-shot acquisition. Here, we propose to replace the scanning system by two highly reflective ($\sim$90 %) mirrors inserted between the lens and the camera as shown in Fig. 1(a). The two mirrors are set parallel with the reflective surfaces facing each other (Fabry–Perot (FP)), but with the laser beam slightly off-axis with respect to the mirror surfaces. The off-axis FP spatially separates the transmitted beams as a function of the round-trip number in the cavity. The successive transmitted beams have experienced a free propagation length of approximately twice the distance between the mirrors (2e). This configuration allows a snapshot of the beam’s spatial profile around its focus as schematically represented in Fig. 1(b)(c). For two beams, in crossed configuration, the snapshot quantifies the beam overlap quality.
Experimental results will be shown during the conference, with the characterization of the individual beams and the quantification of the spatial overlap quality. The device requires a very low light intensity. Different solutions allow to use it in parallel with a running pump-probe experiment. This monitors the beam crossing quality in real time avoiding potential artefacts.

Figure 1 (a) schematic representation of the experimental setup: the two beams are focused with their own focal lens (L1 and L2) and are recombined with a beam splitter (BS). A beam sampler (GS) sends the beams to the off-axis-FP before reaching the camera. Schematic focusing snapshot for (b) a single beam and for (c) two beams in crossed configuration. The following sub-images correspond to the spatial profile around their focus. From left to right, the beams cumulate 2e free propagation distance, with e the separation between the FP-mirrors.

Orateur: M. Madhusoothanan Rajaram (Université Lyon 1, CNRS, Institut Lumière Matière, UMR5306, F-69100, Villeurbanne, France)

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RJP2.pdf

16:40 Quizz Time!

17:00 Conference Cocktail