Merging Optomechanics and Photonics: A New Frontier in Multi-Physics Sensing
Optomechanical sensors are a groundbreaking class of MEMS devices, offering ultra-high sensitivity, wide bandwidth, and seamless integration with silicon photonics. These sensors enable diverse applications, including accelerometry, mass spectrometry, and gas detection. Optical sensors, leveraging photonic integrated circuits (PICs), have also shown great potential for gas sensing.
This PhD focuses on developing a hybrid multi-physics sensor, integrating optomechanical and optical components to enhance sensing capabilities. By combining these technologies, the sensor will provide unprecedented multi-dimensional insights, pushing MEMS-enabled silicon photonic devices to new limits.
At CEA-Leti, you will access world-class facilities and expertise in MEMS fabrication, photonics, and sensor integration. Your work will involve:
-Sensor Design – Using analytical Tools and simulation software for numerical analysis to optimize device architecture.
-Cleanroom Fabrication – Collaborating with CEA’s expert teams to develop the sensor.
-Experimental Characterization – Conducting optomechanical and optical evaluations.
-Benchmarking & Integration – Assessing performance with optics, electronics, and fluidics.
This PhD offers a unique chance to merge MEMS and silicon photonics in a cutting-edge research environment. Work at CEA-Leti to pioneer next-generation sensor technology with applications in healthcare, environmental monitoring, and beyond. Passionate about MEMS, photonics, and sensors? Join us and help shape the future of optomechanical sensing!
Electronic effects dans les cascades de collisions dans le GaN
In radiation environments like space and nuclear plants, microelectronic devices are subject to intense flux of particles degrading the devices by damaging the materials they are made of. Particles collide with atoms of the semi-conducting materials, ejecting them for their lattice site. Those displaced atoms also collide and set in motion a new generation of atoms, and so on, leading to a cascade of collisions which creates defects in the material. Moreover, primary or secondary particles (created following interaction with a neutron for example) also specifically interact with electrons of the target material, and lose kinetic energy in doing so by promoting electrons to higher energy bands. This aspect is called electronic stopping. Simulations of collision cascades must therefore describe both nuclei-nuclei collisions and electronic stopping effects.
The preferred method for collision cascades simulations at the atomic scale is Molecular Dynamics (MD). However, electronic effects are not included in this method as electrons are not taken into account explicitly. To circumvent this issue, additional modules have to be employed on top of MD to model electronic effects in a collision cascade. The state-of-the-art regarding electronic stopping simulation of a projectile in a target material is the real time - time dependent density functional theory (RT-TDDFT). The purpose of this thesis is to combine MD and RT-TDDFT to perform collision cascades simulations in GaN and study the influence of electronic effects. In addition to skills common to all thesis, the candidate will develop very specific skills in different atomic scale simulation methods, solid state physics, particle-matter interactions, linux environment and programming.
Measurement of the speed of sound in H2 and He, key components of gas giant interiors.
The goal of this thesis is to study hydrogen-helium mixtures in the fluid phase under high pressure and high temperature using Raman and Brillouin spectroscopy. The experiments will be conducted in a diamond anvil cell with laser heating, allowing exploration of a wide range of pressure and temperature conditions representative of the interiors of gas giant planets (1-300 GPa, 300-4000 K). Raman spectroscopy will be used to probe possible chemical changes occurring under extreme conditions, while Brillouin spectroscopy will provide access to the adiabatic sound velocity and the equations of state of these fluid mixtures. These data will be particularly useful for improving the modeling of Jupiter and Saturn’s interiors.
The solid-state systems, presently considered for quantum computation, are built from localized two-level systems, prime examples are superconducting qubits or semiconducting
quantum dots. Due to the fact that they are localized, they require a fixed amount of hardware per qubit.
Propagating or “flying” qubits have distinct advantages with respect to localised ones: the hardware footprint depends only on the gates and the qubits themselves (photons) can be created on demand making these systems easily scalable. A qubit that would combine the advantages of localised two-level systems and flying qubits would provide a paradigm shift in quantum technology. In the long term, the availability of these objects would unlock the possibility to build a universal quantum computer that combines a small, fixed hardware footprint and an arbitrarily large number of qubits with long-range interactions. A promising approach in this direction is to use electrons rather than
photons to realise such flying qubits. The advantage of electronic excitations is the Coulomb interaction, which allows the implementation of a two-qubit gate.
The aim of the present Phd will be the development of the first quantum-nanoelectronic platform for the creation, manipulation and detection of flying electrons on time scales down to the picosecond and to exploit them for quantum technologies.
Relationship between the nature of hard carbons and the properties of electrodes for Na-ion batteries
Hard carbons are the most commonly used negative electrode materials in Na-ion batteries. Their capacity exceeding 300 mAh/g, low operating voltage, long lifespan, and power performance make them the best option for commercializing Na-ion batteries. However, several challenges remain to approach the performance of low-impact Li-ion technologies like LF(M)P/graphite. One major limitation is their low volumetric density. Their disordered nature and resulting microporosity lead to a lower skeletal density compared to graphite. This significantly affects both the volumetric and gravimetric energy densities due to the difficulty of compressing the electrodes.
The main objective of this thesis is to establish a link between the material's skeletal density and the electrode's calendering capability to reduce its porosity. First, we will evaluate the relationship between the structure, morphology, and surface state of hard carbon and the electrode's density. We will attempt to understand the impact of calendering on the material’s properties. Then, we will assess the tortuosity and conductivity of hard carbon electrodes to predict their performance. Finally, we will work on improving and optimizing the electrodes in terms of energy densities, focusing particularly on electrode formulations.
Measuring quantum decoherence and entanglement in attosecond photoemission
The PhD project is centered on the advanced study of attosecond photoemission dynamics. The objective is to access in real time decoherence processes induced, e.g., by electron-ion quantum entanglement. To that aim, the young researcher will develop attosecond spectroscopy techniques making use of a new high repetition rate Ytterbium laser.
Detailed summary :
In recent years, there has been spectacular progress in the generation of attosecond (1 as=10-18 s) pulses, awarded the 2023 Nobel Prize [1]. These ultrashort pulses are generated from the strong nonlinear interaction of short intense laser pulses with gas jets [2]. They have opened new prospects for the exploration of matter at the electron intrinsic timescale. Attosecond spectroscopy allows studying in real time the quantum process of photoemission and shooting the 3D movie of the electron wavepacket ejection [3, 4]. However, these studies were confined to fully coherent dynamics by the lack of experimental and theoretical tools to deal with decoherence and quantum entanglement. Recently, two techniques have been proposed to perform a quantum tomography of the photoelectron in its final asymptotic state [5, 6].
The objective of the PhD project is to develop attosecond spectroscopy to access the full time evolution of decoherence and entanglement during the photoemission process. Quantum tomographic techniques will be implemented on the ATTOLab laser platform (https://iramis.cea.fr/en/lidyl/atto/attolab-platform/) using a new Ytterbium laser source. This novel laser technology is emerging, with stability 5 times higher and repetition rate 10 times higher than the current Titanium:Sapphire technology. These new capabilities represent a breakthrough for the field and allow, e.g., charged particle coincidence techniques, to study the dynamics of photoemission and quantum entanglement with unprecedented precision.
This PhD project is performed in the frame of a recently funded European Network QU-ATTO (https://quatto.eu/), providing an advanced training to 15 young researchers, and opening many opportunities of joint work with European laboratories. In particular, strong collaborations are already ongoing with the groups of Prof. Anne L’Huillier in Lund, and Prof. Giuseppe Sansone in Freiburg. Due to the Mobility Rule, candidates must not have resided (work, studies) in France for more than 12 months since August 2022.
The student will receive solid training in ultrafast optics, atomic and molecular physics, attosecond science, quantum optics, and will acquire a broad mastery of XUV and charged-particle spectroscopy techniques.
References :
[1] https://www.nobelprize.org/prizes/physics/2023/summary/
[2] Y. Mairesse, et al., Science 302, 1540 (2003)
[3] V. Gruson, et al., Science 354, 734 (2016)
[4] A. Autuori, et al., Science Advances 8, eabl7594 (2022)
[5] C. Bourassin-Bouchet, et al., Phys. Rev. X 10, 031048 (2020)
[6] H. Laurell, et al., Nature Photonics, https://doi.org/10.1038/s41566-024-01607-8 (2025)
Development and study of laminated composite material with carbon nanotubes functionalisation dedicated to launcher linerless cryogenic tank
The use of composite materials in the space field has led to great weight improvements. To continue to achieve significant weight gain, composite cryogenic tank is the next technological application to reach by replacing the current metal alloy cryogenic propellant tanks. Lighter reinforced organic matrix composite materials (that are at least as efficient from a mechanical, thermal, chemical and ignition resistance point of view) are a realistic target to be reached that has been explored in recent years. Many research approaches tend to answer to this technological lock, but the potentialities of Carbon NanoTubes (CNTs) in terms of mechanical and physical properties, need to be explored deeper.
A first phase to assess the interest of CNTs for space applications (collaboration CNES/CEA/I2M/CMP Composite) was carried out to associate CNTs with a cyanate ester matrix in layered composite materials through three processes: (i) transfer of aligned CNTs mats by hot pressing (ii) dispersion of entangled CNTs mixed with resin, or (iii) growth of nanotubes aligned directly on the dry ply. Knowing mechanical and thermal loads, the aim is to demonstrate the efficiency of CNTs and influence of their characteristics with regard to damage tolerance of the material and consist in delaying the cracking process of the composite nearby the CNT layer and thus blocking the percolation of the cracking network which leads to the loss of tightness. For the preferred development process identified, the aim of this doctoral work is now to consolidate the material functionalisation with CNTs (shape, density, etc.) and the understanding of the mechanical behaviour (at room temperature and at low temperature) for the development of the layered material integrating CNTs.
Knowing the potential final application as cryogenic tank or for the improvement of structural materials sustainability in dual application, relevant tests will be performed to demonstrate the impact in terms of damage development and tightness in comparison with the same material without CNTs.
Alternatives to perfluorinated compounds for water-repellent and oil-repellent treatments of textiles used for NRBC personal body protection
Finding alternatives to fluorinated compounds (PFAS) involves very diverse application areas. Among them, the treatment of technical textiles to make them water- and oil-repellent is a major challenge for manufacturing protective clothing against both aqueous and oily contaminants. Our laboratory is developing such alternatives by covalently grafting molecules onto fibers selected from those already used for technical textiles. The thesis will focus on experimental work with two components. The first component will consist of improving and qualifying, at a semi-industrial level, the water- and oil-repellent properties already obtained and qualified according to current standards (water and oil droplet sliding, slow impregnation of oil droplets) using our nanometric chemical coatings. The second component will be dedicated to optimizing the weave structure, in conjunction with the chemical treatment, to determine the optimal weave based on the desired properties. The work will be carried out in close contact with a technical textile manufacturer and with ENSAIT in Roubaix.
Study of the thermomechanical properties of solid hydrogen flows
IRIG's Department of Low Temperature Systems (DSBT) is developing several research themes around cryogenic solid hydrogen and its isotopes. The applications of this research range from the production of renewable micrometre-sized solid hydrogen targets for the generation of high-energy protons for laser-plasma acceleration, to the formation and injection of millimetre- or centimetre-sized hydrogen ice cubes for the supply and control of plasma in fusion reactors using magnetic or inertial confinement. A cross-cutting issue in these applications is the need for a detailed understanding of the mechanical properties of solid hydrogen, in order to gain a better understanding of the physics of extrusion and target production, as well as the formation and acceleration of icicles for injection into fusion plasmas.
The subject of this thesis focuses on the study of solid hydrogen extrusion under pressure. Using this technology, the DSBT has been developing several cryostats for over 10 years, enabling the production of ribbons of solid hydrogen, ranging in size from a few millimetres to a few tens of micrometres, extruded at speeds of a few millimetres per second.
The main objective of the research is to gain a better understanding of extrusion mechanisms to enable the development of numerical predictive tools for extrusion system design. This experimental thesis will be based on cryogenic rheometry using a capillary rheometer and/or a duvet experiment developed during a previous thesis. This study will be carried out in collaboration with the Laboratoire de Rhéologie et Procédés at Grenoble Alpes University.
Chiral Superconductors and Thermal Transport
In this PhD project, we intend to probe two well-known unconventional superconductors with thermal transport, through an original approach combining macroscopic and microscopic probes. These superconductors are UPt3 and UTe2, chosen because they address two issues currently under hot debate in the international community, that could strongly benefit from this new approach. UPt3 addresses the question of topological superconductivity, while UTe2 requires a clear identification of its spin-triplet superconducting order parameter.
Topological superconductivity is an active subject on the theoretical side and because of its potential interest in the field of quantum engineering. However, unambiguous experimental results are scarce, and we intend to focus here on UPt3, the first ever superconductor demonstrating the existence of transitions between superconducting phases, together with convincing evidences for chiral superconductivity. The goal is to probe predictions on the existence of an anomalous (zero field) thermal Hall effect, which would arise from the chiral edge currents.
A new approach is proposed, combining a newly designed set-up for the macroscopic measurement of thermal conductivity and thermal Hall effect, together with a microscopic probe realizing Scanning Thermal Spectroscopy. This will be realized thanks to a collaboration between two labratories in Grenoble: a team Pheliqs, mastering high quality crystal growth of these systems together with low temperature thermal transport measurements, and two teams in Néel, experts in Scanning SQUID microscopy and microscopic thermal measurements down to sub-Kelvin temperatures.
With this project, the PhD student will acquire very broad skills, ranging from sample preparation, low temperature instrumentation, and major actual issues in the field of quantum materials.