Novel spin qubits for quantum computing
Quantum RAM (QRAM) is a key quantum computing resource featuring in many theoretical
proposals that has never been demonstrated in experiment. A QRAM is a quantum memory in which
one can read or write quantum information to a superposition of memory cells [1]. Such a device
is powerful as a tool for implementing a plethora of quantum algorithms, including Grover’s search
algorithm [2, 3], quantum chemistry [4, 5], quantum cryptography [6] and quantum machine learning
[7], and is regarded by many as essential for a future quantum computer. It has also proved difficult
to realise due to the complexity of implementing the quantum addressing of quantum storage [8, 9].
This PhD project will fit into a wider ongoing project to develop a QRAM using individual solid
state paramagnetic spin defects coupled to superconducting devices. The core aim of this project is
to investigate novel spin systems and device designs for the purposes of realising a scalable QRAM.
Novel high-gyromagnetic-ratio spin species will reach new regimes of spin-circuit coupling that were
previously inaccessible. The use of silicon as a substrate will allow future devices to reach higher
device quality factors and enable advanced device architectures by leveraging the maturity of silicon
device fabrication. High-spin nuclei such as 167Er will also be investigated, enabling experiments with
high-coherence nuclear spin qudits. These developments will expand the frontiers of a new hybrid
quantum device platform with exciting possibilities both for future quantum information processing
architectures and fundamental physics experiments
Developing a quantum router based on a hybrid spin superconducting circuit architecture
A QRAM is a quantum memory in which one can read or write quantum information to a superposition
of memory cells. Such a device is powerful as a tool for implementing a plethora of quantum
algorithms and is regarded by many as essential for a future quantum computer. It has also proved
di&cult to realise due to the complexity of implementing the quantum addressing of quantum
storage. This PhD work takes part in an e,ort aimed at using recently developed techniques in single
spin detection, spectroscopy and coherent control to demonstrate a quantum router, the unit cell of a
QRAM, using electron and nuclear spins in the solid state. The PhD work will consist of implementing
CSWAP gates schemes on Erbium defects in calcium tungstate in order to demonstrate a four-qubit
QRAM unit cell.
Investigation of Very High Cycle Fatigue Behavior of 13-4 Martensitic Stainless Steel Manufactured by Laser Metal Deposition: Influence of Microstructure, Post-treatments and Temperature Project
Recent research on 13-4 martensitic stainless steel manufactured by metal additive manufacturing, particularly using the Laser Metal Deposition (LMD) process, has made it possible to obtain materials with good mechanical properties. Following this optimization phase, current work is now focused on studying their Very High Cycle Fatigue (VHCF) behavior, which is a critical criterion for components subjected to repeated loading under severe operating conditions.
Fatigue is one of the main causes of failure in metallic components during service. This thesis therefore aims to understand and model the fatigue behavior of LMD-produced 13-4 steel. The work will investigate the influence of microstructure, thermomechanical treatments, and testing conditions on crack initiation and propagation during mechanical loading.
Experimental investigations will be carried out using ultrasonic fatigue testing devices. Failure mechanisms will be analyzed through multi-scale characterization techniques such as EBSD, SEM, and TEM. The final objective is to develop a predictive model capable of estimating the service life of components under operating conditions.
Characterization and Understanding of Degradation Mechanisms in Encapsulation Materials Used in New-Generation Silicon Photovoltaic (PV) Modules under Humidity and UV Stress
New-generation photovoltaic technologies (TOPCon, SHJ, tandems) are particularly sensitive to environmental stressors, including humidity (Damp Heat, DH), UV radiation, and thermal cycling. These stresses accelerate the degradation of encapsulation materials (EVA, POE, TPO), leading to performance losses in modules—such as reduced transparency, delamination, metal contact corrosion, and Potential-Induced Degradation (PID). Despite their increasing adoption, these novel encapsulants lack long-term durability data, while widely used EVA exhibits premature aging (degradation after 10–15 years of exposure). The combined degradation mechanisms (DH + UV + temperature) remain understudied, yet they reflect real-world exposure conditions
This thesis aims to identify and understand the physicochemical degradation mechanisms of polymer encapsulants under coupled stressors, focusing on:
- Multi-scale analysis (chemical structure, optical properties, microstructure) of materials during accelerated aging
- Development of an experimental protocol replicating real-world conditions (coupled DH/UV stress) to assess material resilience
- Study of additive roles in encapsulant degradation, including UV absorbers, peroxides etc.
Growth of FAPbBr3 by CSS for X-ray detection
Lead halide perovskites, and particularly hybrid organic-inorganic materials based on formamidinium, possess exceptional optoelectronic properties that have been intensively exploited for photovoltaic (PV) applications. Within this family of materials, FAPbBr3 is also particularly promising for X-ray detection in medical applications. However, this technology requires the ability to deposit thick layers (>100 µm) over large areas. CEA-LITEN has developed an innovative approach for depositing inorganic perovskites using close-space sublimation (CSS), which meets these criteria. Very recently, it has been shown that it is possible to deposit FAPbBr3 using this method, marking a world first.
However, the growth mechanisms of FAPbBr3 and hybrid perovskites via CSS are largely misunderstood, and the possibilities offered by this deposition method are yet to be fully explored. Furthermore, these results are also extremely promising for PV applications, as similar growth is expected by substituting Br to form FAPbI3.
This thesis aims to (i) determine and optimize the growth conditions via CSS for FAPbBr3 layers, (ii) understand the growth mechanisms of FAPbBr3 through advanced characterizations (in-situ and ex-situ), and (iii) optimize devices for X-ray detection. The extension of this work to FAPbI3 for PV applications is also anticipated. The novelty of this approach and the potential to address multiple applications offer prospects for publications and patents.
Development of durable and flexible KNN piezoelectric materials: toward an alternative to lead-based ceramics and fluorinated polymers
The project aims to develop lead-free and PFAS-free (perfluoroalkyl and polyfluoroalkyl substances) piezoelectric thin films based on potassium sodium niobate (KNN) that are compatible with flexible substrates, in direct response to the growing regulatory and environmental constraints affecting conventional piezoelectric materials. PZT ceramics (lead titanate-zirconate) and PVDF polymers (polyvinylidene fluoride), which currently dominate the market, have significant limitations related to lead toxicity and the environmental persistence of PFAS, respectively. In this context, identifying sustainable and integrable alternative materials is a strategic priority for the CEA, particularly for flexible electronics applied to medical, embedded, and sustainable devices.
KNNs are among the most promising alternatives due to their high piezoelectric properties and high Curie temperature. However, their integration in the form of thin films remains severely limited by crystallization temperatures exceeding 600 °C, which are incompatible with polymer substrates. The project’s objective is to overcome this barrier by developing an innovative sol-gel combustion deposition process, enabling localized or global crystallization at low temperatures (<350 °C), compatible with flexible substrates. Beyond the KNN system, this approach could constitute
Development of red and RGB µLEDs for microdisplays and high-speed communication
Background: MicroLEDs (µLEDs) are a promising technology for the development of high-brightness mini-displays (such as augmented reality glasses or smartwatches). Measuring less than 20 µm in size, these µLEDs are produced by etching a planar structure on sapphire that incorporates InxGa1-xN quantum wells. The emitted wavelength is directly tuned by the indium content x of the quantum wells (x ˜ 15% for blue, 25% for green, 35–40% for red). While nitride semiconductors offer excellent performance in the blue spectrum, efficiency drops sharply as the size of the µLEDs decreases. To overcome this issue, an innovative approach involves microwire technology with a core-shell geometry. This architecture preserves emission efficiency regardless of size and enables data transmission at GHz speeds (technology developed by the Grenoble-based startup Aledia). Despite their strong potential, core-shell microwire LEDs still face a major scientific challenge: achieving red emission. Indium incorporation remains limited to 25%, a threshold insufficient to reach red. This technological bottleneck is currently hindering the emergence of RGB trichromatic µLEDs. Our team has achieved pioneering results in this field, where we created the first InGaN core-shell quantum well at 15% for blue emission and 25% for green emission. Despite these advances, the challenge of achieving red emission remains.
Objectives: A new idea has emerged to go beyond 25% of In-content for core-shell microwire technology and thus aim for the first demonstration of red emission, which led to a patent application in 2025. Preliminary results have proven very promising results, and we wish to continue this work through a thesis with the three main objectives:
- Demonstrate red emission by varying the geometric parameters of the microwires (diameter, etc.)
- Produce red µLEDs
- Produce trichromatic RGB µLEDs in a single growth run
Collaborations: This project relies on close collaboration with the LTM (Laboratory of Microelectronics Technology) for the fabrication of GaN microwire arrays via etching process. Epitaxial studies of core/shell LEDs will be conducted at CEA’s PHELIQS facility using the MOCVD epitaxial setup, incorporating structural and optical analyses. The final step aims to fabricate microwire-based µLED devices using the expertise developed at the Néel Institute via the NanoFab cleanroom.
Why join this project? To gain expertise in epitaxy, semiconductor physics, and optoelectronics. To work in a dynamic and collaborative environment closely linked to the industrial sector. To contribute to the development of next-generation µLEDs for micro-displays and GHz communications.
PhD Funding: This thesis project is funded by the UGA’s Labex “µelectronics.”
Sharper Structural Insight in Nanoelectronics with Dark-Field X-Ray Microscopy
Dark-field X-ray microscopy (DFXM) is an emerging, non-destructive synchrotron technique capable of imaging strain and crystalline defects with 30–100 nm resolution over large fields of view. Recent upgrades at the ESRF and the ID03 beamline have increased X-ray intensity by two orders of magnitude, enabling investigation of the most challenging nanoscale structures produced in cleanroom environments. This PhD aims to exploit DFXM for the analysis of advanced microelectronic architectures subjected to critical thermo-mechanical stress. DFXM will provide 3D mapping of strain, orientation and buried defects in complex devices without sample destruction. A comparative study will be performed against complementary local X-ray techniques also available at synchrotron facilities such as Laue microdiffraction and scanning X-ray diffraction microscopy. Multi-scale correlations will be established with TEM and Raman spectroscopy. Finite-element simulations will support interpretation by modelling the mechanical behavior under thermal or operational loads. The objective is to define a robust methodology for multiscale strain analysis in microelectronics devices.
This PhD will take place at the CEA–Leti on the Nanocharacterization platform and is embedded in a strong ESRF@ID03 collaboration and supports advances in quantum technologies, photonics and energy-efficient microelectronics. This work will contribute to improved reliability and design optimization of next-generation devices.
Orbitronics: time scales involved in orbital to charge conversion processes
Orbitronics is an emerging research field spanning condensed matter physics and materials science to electrical engineering that focuses on the study and manipulation of the electron's orbital angular momentum (OAM). The key idea is to use the OAM of electrons as a means to store, transfer, and process information, similar to how spintronics leverages the electron's spin. Importantly, OAM can be generated by a wide range of material systems and with theoretically much higher efficiency than its spin counterpart, using cheap, environmentally friendly and abundant lightweight elements. Orbitronics thus has both a fundamental interest and technological perspectives that provide an innovative and multidisciplinary framework.
Here, we are targeting oxide interfaces as a rich playground to explore Rashba physics in 2D electron gases (2DEG) and in particular its ability to confert spin or orbit to charge via the Orbital Inverse Rashba Edelstein effect. The LaAlO3/SrTiO3 interface provides an ideal playground to explore this physics and in particular parameters such as crystal orientation and the (LaAlO3) tunnel barrier. These properties will be studied at low-temperature as angular momentum is injected in the dc regime by the spin Seebeck effect. The study will be extended to the ultra-fast regime of the orbital to charge conversion using ultra-fast laser-induced demagnetization of a magnetic layer deposited on top and the measurement of the resulting THz emission. Here, we want to identify the parameters responsible for the decrease in efficiency at the picosecond timescale noted in the first THz emission measurements. Our final aim is to measure the timescales associated to hot electrons and spin/orbital diffusion in this system, which will be the main activity of the PhD student.
Thermodynamic and transport properties of Fe-Ni alloys in the Warm Dense Matter regime
Warm Dense Matter (WDM) lies at the intersection of condensed matter physics and
plasma physics. In particular, it is characterized by temperatures comparable to those of the
Fermi level (1,000 to 10,000 K) and densities on the order of those of solids. In this
state of matter, a thorough understanding of the phase diagram and transport properties, such as
electrical conductivity, is crucial for modeling the magnetospheres of rocky planets,
hydrodynamic instabilities encountered in inertial confinement fusion experiments,
or during giant impacts, such as the one believed to have formed the Moon from the collision between
Earth and Theia.
For several years now, the Laboratory for Matter under Extreme Conditions at CEA DAM Île-de-France developed
an experimental facility (Pulsed Plasma Chamber—EPP) dedicated to the study of WDM. Using
pulsed-power discharges with very high currents (20–500 kA), this experimental facility enables the investigation of
changes in the thermodynamic and transport properties of matter as it transitions from the solid state to
the plasma state over time scales of the order of hundreds of nanoseconds. Very recently, these experiments
have been carried out using an X-ray synchrotron source to evaluate the electronic state density of the plasmas encountered in the EPP experiments.
This PhD will focus on the study of thermodynamic and transport properties of a
binary iron-nickel alloy within a pressure-temperature range associated with giant impacts. To this end, experiments will be conducted both at the CEA DAM Île-de-France site and at a synchrotron facility in order to investigate the thermodynamic, optical, and transport properties of Fe-Ni. The experimental data collected will then be compared with quantum molecular dynamics simulations that provide information, in particular, on the electronic states observed during the experiments. Finally, new theoretical approaches, based on the experimental and numerical results, will need to be proposed in order to improve the modeling of this type of alloy in the WDM regime.