Super-gain miniature antennas with circular polarization and electronic beam steering

Antenna radiation control in terms of shape and polarization is a key element for future communication systems. Directive compact antennas offer new opportunities for wireless applications in terms of spatial selectivity and filtering. This leads to a reduction in electromagnetic pollution by mitigating interferences with other communication systems and reducing battery consumption in compact smart devices (IoT), while enabling also new use modes. However, the conventional techniques for enhancing the directivity often lead to a significant increase of the antenna size. Consequently, the integration of directional antennas in small wireless devices is limited. This difficulty is particularly critical for the frequency bands below 3 GHz if object dimensions are limited to a few centimeters. Super directive/gain compact antennas with beam-steering capabilities and operating on a wideband or on multi-bands are an innovative and attractive solution for the development of new applications in the field of the connected objects. In fact, the possibility to control electronically the antenna radiation properties is an important characteristic for the development of the future generation and smart communication systems. CEA Leti has a very strong expertise in the domain of superdirective antennas demonstrating the potentials of the use of ultra-compact parasitic antenna arrays. This PhD project will take place at CEA Leti Grenoble in the antennas and propagation laboratory (LAPCI). The main objectives of this work are: i) contribution to development of numerical tools for the design and optimization of superdirective compact arrays with beam-steering capabilities; ii) the study of new elementary sources for compact antenna arrays; iii) the realization and experimental characterization of a supergain compact array with circular polarization and beam-steering capabilities. This work will combine theoretical studies and model developments, antenna design using 3D electromagnetic software, prototyping and experimentations.

Design of FD-SOI-specific True Random Number Generator

TRNGs are the essential block of any cryptographic system. Current standards, such as AIS-31, require a stochastic model, which directly relates the model of the physical source of randomness to the entropy of the generated random bits. TRNGs are benchmarked based on their throughput, efficiency and robustness. As such, FD-SOI (Fully Depleted Silicon on Insulator) is a technology well known for its advantages in terms of consumption, but also for the adaptability of its characteristics granted by its unique back bias control acting as a second gate.
This PhD position aims to extend the use of this back gate by studying the opportunities offered by an integrated management of the back gate. By applying a voltage, the BOX allows the adjustment of characteristics at a transistor level. This technique called back biasing, enables the fine-tuning of characteristics and has thus far not been used in the design of security primitives. This technique will be implemented for a FD-SOI specific TRNG based on coherent sampling. Though the novelty and the relevance of the FD-SOI based approach is clear, and motivations to go toward coherent sampling architectures for TRNG have been documented in the literature, the objective of the PhD student will be to bring experimental demonstration, with the support of simulation and modelling of these specific architectures. This will be made possible by a first version of ASIC samples already available at the start of the PhD and the design (by the PhD student) of another ASIC.

Electromagnetic compatibility converter optimization with wide band gap devices for frequency increase

Power Electronics systems aims at converting one shape of Energy into another. From very low power, such as USB power delivery (hundreds of watts) to high power, like electric vehicle drivetrain (hundreds of kW, power scale is large. Power Electronics systems are everywhere, this is why such systems must be optimized to be efficient, compact, profitable and with an optimized environmental footprint.
The emergence of "wide bandgap components" (WBG) revolutionize the efficiency of power converters along with their power density. However, WBG components generate more disturbances in the grid, and could possibly affect even degrade the operation of systems in the immediate environment. There are standards to regulate the amount of disturbances allowed to go outside of the converter environment. The committee in charge of the electromagnetic compatibility aspect is called "the International Special Committee on Radio Interference" (CISPR).
On the contrary, filtering technologies did not evolve as fast as WBG components and the main difficulty today to turn a proof of concept into an industrial product is to meet the electromagnetic compatibility standards.

The objectives of the PhD are the followings:
- Topology Study of different types of filter (passive and active)
- Study and characterization of magnetic material, their design,, efficiency in function of the frequency etc.
- Propose filtering solutions (materials, integration, modulation etc.)
- Skills improvement on EMC modelling with a given "use case", and take into account, parasitic elements, couplings by radiation along with material performances.

The PhD should give answer about frequency increase, depending on the use case, based on WBG components and relevancy of such technology on applications with strong constraints (EMC, cost, volume, and efficiency).

This PhD will take place at CEA Grenoble, in the System Department, in the laboratory of Electronics for power and Energy. CEA environment is very transversal; the candidate will be able to feed his researches with engineers from the system department. The candidate, after electrical habilitation, will have access to the laboratories of power Electronics to make his experimental testing.

The candidate must have skills in power Electronics, in particular the topologies of power converter, components (active and passive) and attractions for modelling complex systems thanks to finite elements software and experimental testing. The candidate must have analytical and critical skills and propose scientific experiment during the PhD.

Stabilizer-universal graph states for robust quantum networks and quantum error correction

The last years have seen notable advances in quantum technologies, consolidating the development of basic requirements for the deployment of future quantum networks. Such networks are essential to distributed quantum information applications, and may serve various purposes, e.g., enabling the transmission of quantum states between physically distant parties, or improving the computational capabilities of quantum computers by combining multiple quantum processors. When only local operations and classical communication (LOCC) are allowed, the initial quantum state shared between the parties plays a key role, and may both enable specific applications, or provide the means to answer unsettled theoretical questions.
This PhD project aims at exploring k-stabilizer universal quantum states, that is, n-qubit quantum states that allow inducing any stabilizer state on any subset of k qubits, by using LOCC protocols only. Stabilizer states can be described, up to local unitaries, by the formalism of graph states, representing one of the most important classes of multipartite entanglement, and a powerful resource for many multipartite quantum protocols. The goal of the thesis is threefold. A first objective is to develop deterministic methods to construct k-stabilizer universal graph states on a number of qubits n quadratic in k (theoretical bound), thus improving the scalability and efficiency with respect to current state of the art. A second objective is to investigate the robustness of the derived protocol, for preparing a desired quantum stabilizer state on a subset of k qubits, to potential threats posed by malicious parties or qubit losses. Finally, the last objective of the thesis is to identify connections and implications between k-stabilizer universal graph states, robustness, and quantum error correction, as a way to devise new constructions of quantum error correcting codes of independent interest, or to increase the reliability of quantum networks.

Security blind spots in Machine Learning systems: modeling and securing complex ML pipeline and lifecycle

With a strong context of regulation of AI at the European scale, several requirements have been proposed for the "cybersecurity of AI" and more particularly to increase the security of AI systems and not only the core ML models. This is important especially as we are experience an impressive development of large models that are deployed to be adapted to specific tasks in a large variety of platforms and devices. However, considering the security of the overall lifecycle of an AI system is far more complex than the constraint, unrealistic traditional ML pipeline, composed of a static training, then inference steps.

In that context, there is an urgent need to focus on core operations from a ML system that are poorly studied and are real blind spot for the security of AI systems with potentially many vulnerabilities. For that purpose, we need to model the overall complexity of an AI system thanks to MLOps (Machine Learning Operations) that aims to encapsulate all the processes and components including data management, deployment and inference steps as well as the dynamicity of an AI system (regular data and model updates).

Two major “blind spots” are model deployment and systems dynamicity. Regarding deployment, recent works highlight critical security issues related to model-based backdoor attacks processed after training time by replacing small parts of a deep neural network. Additionally, other works focused on security issues against model compression steps (quantization, pruning) that are very classical steps performed to deploy a model into constrained inference devices. For example, a dormant poisoned model may become active only after pruning and/or quantization processes. For systems dynamicity, several open questions remain concerning potential security regressions that may occur when core models of an AI system are dynamically trained and deployed (e.g., because of new training data or regular fine-tuning operations).

The objectives are:
1. model security of modern AI systems lifecycle with a MLOps framework and propose threat models and risk analysis related to critical steps, typically model deployment and continuous training
2. demonstrate and characterize attacks, e.g., attacks targeting the model optimization processes, fine tuning or model updating
3. propose and develop protection schemes and sound evaluation protocols.

Power and data transmission via an acoustic link for closed metallic environments

This thesis focuses on the transmission of power and data through metal walls using acoustic waves. This technology will eventually enable the powering, reading and control of systems placed in areas enclosed in metal: pressure vessels, ship hulls and submarines, etc.
As electromagnetic waves are absorbed by metal, it is necessary to use acoustic waves to communicate data or power through metal walls. These are generated by piezoelectric transducers bonded to either side of the wall. Acoustic waves are poorly attenuated by metal, resulting in numerous reflections and multiple paths. It is therefore necessary to use multi-carrier communication techniques (e.g. OFDM), in order to achieve robustness and high throughput.
The aim of this thesis is to develop a robust technology demonstrator for remote powering and acoustic data communication through metal walls. This work will be based on advanced modeling of the acoustic channel to optimize the performance of the power and data transmission device. It will also involve developing innovative electronic building blocks to determine and maintain an optimum power transmission frequency, impacted by environmental conditions and typically by temperature.
The ultimate goal of this thesis will be the development and implementation of an OFDM communication system embedded in an FPGA and/or microcontroller to send sensor data through a metal wall of variable thickness. Limitations due to channel and electronic imperfections will lead to the invention of a large number of compensation methods and systems in the digital and/or analog domain. Work will also be carried out on the choice of piezoelectric transducers and channel characterization, in conjunction with the acoustic wave activities of the acoustic power transmission laboratory.

Advanced RF circuit design in a system and technology co-optimization approach

This thesis addresses the two major challenges facing Europe today in terms of integrating the communication systems of the future. The aim is to design RF integrated circuits using 22nm FDSOI technology in the frequency bands dedicated to 6G, which will not only increase data rates but also reduce the carbon footprint of telecoms networks. At the same time, it is essential to consider the evolution of silicon technologies that could improve the energy efficiency and effectiveness of these circuits. This work will be carried out with an eye to the design methodology of radio frequency systems.
Within the framework of the thesis, the objective will be broken down into three phases. Firstly, simulation tools will be developed to predict the performance of Leti's future 10nm FDSOI technology. The second stage will involve identifying the most relevant architectures available in the literature for the application areas envisaged for the technology. A link with upstream telecoms projects will be systematically established to ensure that the candidate understands the systems' challenges.
Finally, in order to validate the concepts developed, the design of an LNA and a VCO as part of an ongoing project in the laboratory will be proposed.

The candidate will join a large team that works on new communication systems and addresses aspects of architectural study, modeling and design of integrated circuits. The candidate must have serious skills in the design of integrated circuits and radio frequency systems as well as good ability to work in a team.

Disruptive RF Transceivers for Full Duplex 6G Communications

This thesis is an opportunity to participate in the development of future telecommunications systems in the 10-15 GHz band, in partnership with the best research centers in Europe working on the subject.
Over the past 20 years, wireless communications systems have continued to evolve and offer new services. Today, such is their success that frequency bands below 10 GHz are saturated, and the focus is now on higher frequencies.
To maintain sufficient range, beamforming is needed to compensate for the higher attenuation associated with propagation. Beamforming architectures are often costly in terms of power consumption and generate losses when implementing phase shifters, but they are also a tremendous opportunity for innovation. What's more, the development of 6G can only be achieved by significantly reducing base station power consumption and adding new functionalities such as full duplex (using the same band to receive and transmit simultaneously). To achieve these ambitious goals, new architectures need to be developed, and this is the aim of the European project that brings together Ericsson (Sweden), ETH Zurich (Switzerland), the University of Twente (Netherlands) and CTTC (Spain). The candidate will therefore be working in an ambitious context with partners of excellence.

X-ray attacks of advanced technology integrated circuits

The CESTI laboratory in Grenoble is responsible for the safety evaluation of products (commercial or prototype).
or prototypes). A wide range of tests can be carried out as part of these evaluations, including those designed to
observe the target's behavior when faults are injected into integrated circuits. Fault injection
consists of perturbing the system by various means in order to obtain different behaviours than those
and thus potentially bypass security countermeasures.
CESTI is constantly on the lookout for new avenues of attack, including X-ray attacks, for which CESTI has developed a number of new techniques.
attacks, for which CESTI has been a forerunner. The laboratory has successfully demonstrated the possibility
of X-ray attacks by modifying memory cells or single transistors with a nano-focused
beam.
In order to make further progress on realistic attacks and develop them on the latest-generation
generation components, this thesis will explore the intrinsic limits, potential applications and physical effects
associated with these ionizing radiation disturbances.
The thesis will include an experimental paassociated with these ionizing radiation disturbances.
The thesis will include an experimental part, using the ESRF beam or reducing the power of the
of the attacker using a laboratory X-ray generator, to attack various types of components, and it will also
also include a more theoretical part with simulation to understand the physical effects, in collaboration with
effects in collaboration with ONERA, and an a analysis of possible new attack paths with these X-ray beams.
beams.
The aim of the thesis will be to obtain a real attack on recent components, reducing the attacker's power to a minimum, and to identify as exhaustively as possible the threat that could be posed by the X-ray beams.
power of the attacker, as well as to define as exhaustively as possible the potential threat
ionizing beam attacks. An opening to other fields such as failure analysis, hardening of
hardening of circuits for space applications.

Signal processing in cybersecurity: development of frequency tools for side-channel attacks and application to voice biometrics

Embedded cryptography on smartcards can be vulnerable to side-channel attacks, based on the interpretation of the information retrieved during the execution of the algorithm. This information leak is generally measured at the hardware level thanks to a consumption signal or electromagnetic radiation. Many methods, based mainly on statistical tools, exist to exploit these signals and to find secret elements.
However, the information used during this process is partial, because the current methods mainly exploit the signal in the time space. The signals being more and more complex, noisy and out of sync, and also very variable from one component to the other, the application of signal processing methods, in particular a time / frequency analysis, makes it possible to obtain additional information from the frequency space. The use of this information can lead to improved attacks. The state of the art presents several methods around side-channel attacks in frequency domain, but they are currently sparsely exploited.
As a first step, the PhD student will be able to use the existing signals and tools to become familiar with the side-channel attacks. He will then be able to rely on the existing literature around frequency attacks, in particular works of G. Destouet [1-2-3] which explore new techniques for filtering, compression, but also pattern detection for the purpose of optimal resynchronization, or for cutting signals in the context of so-called "horizontal" attacks.
These researches will be analyzed deeply and the Phd Student will be able to explore new techniques, for example new wavelet bases, and will test his algorithms on suitable signal bases.
Moreover, the "machine learning" method applied to side-channel attacks is currently studied, and the contribution of frequency data is also a way of improving the use of neural networks. The doctoral student will be able to rely on the different methods already existing in time and expand them thanks to wavelet transforms, in order to improve learning.
These different methods are applicable to signals analysis in voice biometrics. The Phd student will be able, among other things, to study neural networks using frequency data, adapted to audio signals obtained in biometrics, also using wavelets or so-called “cepstral” analysis.

At CEA-Leti Grenoble the student will be in a reference laboratory in the evaluation of high security devices(http://www.leti-cea.fr/cea-tech/leti/Pages/innovation-industrielle/innover-avec-le-Leti/CESTI.aspx).

[1] Gabriel Destouet Ondelettes pour le traitement des signaux compromettants. (Wavelets for side-channel analysis) https://theses.hal.science/tel-03758771
[2] Gabriel Destouet et al. Wavelet Scattering Transform and Ensemble Methods for Side-Channel Analysis". In : Constructive Side-Channel Analysis and Secure Design. Sous la dir. de Guido Marco Bertoni et Francesco Regazzoni. T. 12244. Series Title : Lecture Notes in Computer Science. Cham : Springer International Publishing, 2021, p. 71-89. isbn : 978-3-030-68772-4 978-3-030-68773-1. doi : 10 . 1007 / 978 - 3 - 030 -68773-1_4.
[3] Gabriel Destouet et al. Generalized Morse Wavelet Frame Estimation Applied to Side-Channel Analysis. ICFSP 2021: 52-57

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