Training

Tristan BERANGER

Theses in preparation in Montpellier, as part of the Doctoral School of Information, Structures, and Systems, in partnership with IES – Institute of Electronics and Systems (laboratory) and MOdélisation et Spectroscopie TéraHertz (MoST) (research team).

Co-supervisors: Dr. J. Torres (IES) and Dr. S. Ruffenach (L2C)

This project is part of the LINkS consortium, funded by the European Commission under the H2020 program and involves top partners from cell biology, biochemistry, theoretical biophysics, and nanotechnology groups, as well as SMEs. It is a scientifically challenging project that plans to change the paradigms of the self-organization of intracellular living matter with a radically new vision of protein-protein attractive mechanisms. It will develop a radically new breakthrough technology of lab-on-a-chip THz biosensor.

We seek to lay the foundations of a new technology, which will allow the study of intermolecular electrodynamic forces in the real complexity of biological systems and, in the long term, address proteomic analysis, biomarker identification, and associated personalized therapies.

Maria SZOŁA

Transnational joint supervision thesis, within the framework of IRP TERAMIR

Laboratories: L2C, University of Montpellier, France – IHPP –PAS, Poland

Co-supervisors: Dr. F. Teppe (L2C) and Dr. G. Cywinski (IHPP PAS)

Dirac matter is a newly discovered class of condensed matter system, described by the Dirac equation. Distinguished examples are topological insulators, graphene, or Weyl semimetals. It appears as if HgCdTe would also be a good candidate, while its bandgap Eg = 0 at some concentration of Cd, temperature, or pressure. Then, HgCdTe becomes similar to graphene where electrons act as 2D massless fermions with zero-bandgap conical bands.

The main aim of this research is to observe a phase transition between the semimetal and semiconductor phases in HgCdTe, bulk material, and HgTe quantum wells. This transition would be induced by the hydrostatic pressure applied to the sample. To observe it, THz transmission through the samples in the magnetic field will be investigated.

In order to analyze the obtained data, the simplified Kane model will be used and, if necessary, a new model containing a contribution from the hydrostatic pressure will be developed.

This research will provide an opportunity to investigate the spectral properties of THz excitations of two-dimensional gas of massless Dirac fermions.

Sebastien GEBERT

PhD position in the EU Horizon 2020 Marie Skłodowska-Curie MSCA-ITN Project TeraApps (Doctoral Training Network in Terahertz Technologies for Imaging, Radar, and Communications Applications)

This thesis is an investigation of the terahertz/infrared emission and absorption spectroscopy of various Dirac materials in magnetic fields. The studied materials range from graphene to different topological insulators (TIs) to novel Dirac/Weyl semimetals.

The experimental results and complementary theoretical calculations show that the emission arising in the incipient Landau quantization regime is favored both by the finite rest mass and the specific band dispersion of HgTe QWs. The latter breaks the series of equidistantly spaced LL subsets and thus suppresses non-radiative Auger recombination inherent in graphene. At the same time and against all expectations, an emission signal was also observed from some graphene samples. Finally, some emission has also been obtained from Dirac-/Weyl-semimetals.

The preliminary results show that the emission may be linked to the semi-classical CR, but deeper analysis is needed to confirm these first results and understand this phenomenon.

Yoann MERIGUET

This project proposes to develop new biological sensors operating at terahertz (THz) frequencies based on low-cost field-effect transistors (LC-FET) and specially designed transistors with silicon nanowires (NW-FET). The development of these sensors, which operate in conditions close to those found in the human body, will be carried out from a unique multidisciplinary perspective involving theoretical and experimental physicists, molecular biologists, and electronics engineers working on theory, manufacturing, experiments, and numerical simulations.

These biosensors will enable the spectral signatures of proteins to be determined either in an aqueous medium (near field) or in powder form (far field), whose response is not generally observable due to the high absorption of water in this spectral range. The design, manufacture, and characterization of these reliable and extremely sensitive biosensors will open up new avenues for non-drug medical interventions and for the sustainable management of environmental resources (water, public health).

Anastasiia Kudashova

PhD position in the EU Horizon 2020 Marie Skłodowska-Curie MSCA-ITN Project TeraApps (Doctoral Training Network in Terahertz Technologies for Imaging, Radar, and Communications Applications)

There are various techniques for measuring water content profiles in situ over time, such as X-ray tomography and nuclear magnetic resonance (NMR). These techniques are currently applied to wood samples, but they are difficult to implement due, among other things, to the ionizing nature of the beam used to scan the sample. A technique using a non-ionizing terahertz (THz) beam is being researched by the "Terahertz Spectroscopy" team at the Charles Coulomb Laboratory (University of Montpellier). As part of a thesis on the wood used in the manufacture of clarinets, and in collaboration with the Wood team at the Mechanics and Civil Engineering Laboratory (University of Montpellier), preliminary tests using this technique on wood have been set up. Unfortunately, lockdown has prevented the developed device from being used to its full potential.

The objective of this PFE is therefore to finalize the setup of the experiments, calibrate the measurements, conduct water diffusion experiments in poplar samples, and compare the results obtained with conventional "weighing" measurements and numerical diffusion simulations based on data from the literature.

We recently demonstrated that proteins undergo global oscillations and resonate at specific frequencies. This discovery suggests that cellular proteins could communicate remotely via wireless antennas. If this were the case, our data would open up a new field of investigation for studying the biological functions of proteins, particularly for analyzing the regulation of protein/protein interactions. With this project, we are beginning a program of spectral characterization of a sample of proteins in order to create a database. The ultimate goal is to confirm the existence of wireless electromagnetic signals that would enable inter-protein communication and, ultimately, to identify ways to modulate these signals in order to regulate the function of proteins involved in the development of certain diseases.

Agriculture in France uses 3 billion m3 of water for irrigation, and wastes more than 30% of it every year. To limit water waste in agriculture, it is necessary to know when crops need to be watered. We studied a solution using THz waves to determine the water content of a plant. Depending on the water content of the plant, it is possible to determine its water requirements. However, THz waves are still little known and are still being studied. During this internship, we measured the transmission of THz waves by several leaves.