Training

Tristan BERANGER

Theses currently in progress in Montpellier, as part of the Information, Structures, Systems Doctoral School, in partnership with IES—Institute of Electronics and Systems (laboratory) and the Terahertz Modeling and Spectroscopy (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 leading partners from the fields of cell biology, biochemistry, theoretical biophysics, and nanotechnology, as well as small and medium-sized enterprises (SMEs). It is a scientifically challenging project that aims to revolutionize our understanding of the self-organization of intracellular living matter through a radically new perspective on protein-protein interaction mechanisms. It will develop a radically new, breakthrough lab-on-a-chip THz biosensor technology.

We aim to lay the groundwork for a new technology that will enable the study of intermolecular electrodynamic forces within the true complexity of biological systems and, in the long term, address proteomic analysis, biomarker identification, and related personalized therapies.

Maria SZOŁA

Transnational Joint Supervision Thesis, as part of the IRP TERAMIR project

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

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

Dirac matter is a newly discovered class of condensed matter systems described by the Dirac equation. Notable examples include topological insulators, graphene, and Weyl semimetals. It appears that HgCdTe may also be a good candidate, as its bandgap (E_g) equals zero at certain concentrations of Cd, temperatures, or pressures. In this case, HgCdTe behaves similarly to graphene, where electrons act as 2D massless fermions with zero-bandgap conical bands.

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

To analyze the obtained data, the simplified Kane model will be used, and if necessary, a new model that includes a contribution from hydrostatic pressure will be developed.

This research will provide an opportunity to investigate the spectral properties of THz excitations in a 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 investigates the terahertz and infrared emission and absorption spectroscopy of various Dirac materials in magnetic fields. The materials studied range from graphene to various topological insulators (TIs) and novel Dirac/Weyl semimetals.

The experimental results and complementary theoretical calculations show that the emission, which arises in the incipient Landau quantization regime, is favored by both 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 the non-radiative Auger recombination inherent in graphene. At the same time, and contrary to all expectations, an emission signal was also observed from some graphene samples. Finally, some emission has also been observed in Dirac/Weyl semimetals.

The preliminary results indicate that the emission may be linked to the semi-classical CR, but further analysis is needed to confirm these initial findings and understand this phenomenon.

Yoann MERIGUET

This project aims to develop new terahertz (THz) biological sensors based on low-cost field-effect transistors (LC-FETs) and transistors specifically designed using silicon nanowires (NW-FETs). The development of these sensors, which will operate under conditions close to those of the physiological environment, will be carried out using a unique multidisciplinary approach involving theoretical and experimental physicists, molecular biologists, and electronics engineers working on theory, fabrication, experiments, and numerical simulations.

These biosensors will make it possible to determine the spectral signatures of proteins either in an aqueous medium (near field) or in powder form (far field), whose response is generally not observable due to the high absorption of water in this spectral range. The design, fabrication, and characterization of these reliable and extremely sensitive biosensors will open new avenues for non-pharmaceutical 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 or 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 currently being researched by the “Terahertz Spectroscopy” team at the Charles Coulomb Laboratory (University of Montpellier). As part of a doctoral thesis on the wood used in clarinet making, and in collaboration with the Wood Team at the Laboratory of Mechanics and Civil Engineering (University of Montpellier), preliminary tests using this technique on wood have been conducted. Unfortunately, the lockdown prevented the full utilization of the developed device.

The objective of this final project is therefore to complete the setup of the experiments, calibrate the measurements, conduct water diffusion experiments on 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 may communicate over long distances via wireless antennas. If this were the case, our data could open up a new field of research for studying the biological functions of proteins, particularly for analyzing the regulation of protein-protein interactions. With this project, we are launching a program to perform 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 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 reduce water waste in agriculture, it is necessary to know when crops need to be watered. We studied a solution using THz waves to determine a plant’s water content. Based on the plant’s water content, it is possible to determine its water needs. However, THz waves are still not well understood and are still being studied. During this internship, we measured the transmission of THz waves through several leaves