M/F Design and electromagnetic modelling of whispering gallery mode resonators for a millimetre-wave maser based on electrons on liquid helium
New
- FTC PhD student / Offer for thesis
- 36 months
- Doctorate
This offer is available in English version
This offer is open to people with a document recognizing their status as a disabled worker.
Offer at a glance
The Unit
Laboratoire d'analyse et d'architecture des systèmes
Contract Type
FTC PhD student / Offer for thesis
Working hHours
Full Time
Workplace
31031 TOULOUSE
Contract Duration
36 months
Date of Hire
02/11/2026
Remuneration
2300 € gross monthly
Apply Application Deadline : 05 October 2026 23:59
Job Description
Thesis Subject
The ANR HELIQUANT project aims to develop a millimetre-wave MASER (Microwave Amplification by Stimulated Emission of Radiation, 100-200 GHz) exploiting the population inversion observed in the Landau and Rydberg levels of electrons trapped on the surface of liquid helium. This frequency range corresponds to the "THz gap", where current superconducting technologies remain inefficient. Building this device requires a dielectric Whispering Gallery Mode (WGM) resonator with a very high quality factor, critically coupled to the two-dimensional electron cloud and to an external microwave circuit, within a confined cryogenic environment and under magnetic field. The strong anisotropic Hall conductivity exhibited by electrons under magnetic field modifies the electromagnetic boundary conditions, considerably complicating the resonator design. The thesis aims to design, model, and experimentally validate WGM resonators operating between 100 and 200 GHz, compatible with efficient coupling to the electron cloud on helium under a moderate magnetic field. This involves determining optimal eigenfrequencies, quality factors, and mode volumes, identifying the polarization best suited to cyclotron and Rydberg transitions, and quantitatively explaining the transmission asymmetry already observed experimentally under magnetic field. The work will combine 3D full-wave electromagnetic simulations (FEM solver, HFSS) with analytical approximations in the thin-film limit to model the anisotropic surface conductivity of electrons on helium and its impact on polarization, mode splitting, and non-reciprocal propagation within the resonator. Different coupling strategies (antenna-based coupling, evanescent waveguides) will be compared in order to maximize resonant injection efficiency while suppressing non-resonant transmission. Predictions will be compared with room-temperature vector network analyzer (VNA) measurements carried out on the LAAS characterization platform. Close collaboration with LPS will allow the cryogenic constraints (hermetic cell, leak-tight microwave access) to be integrated into the final design. The thesis is expected to yield an optimal resonator geometry for coupling to electrons on helium, experimental validation of injection efficiency at room temperature, and a predictive model of the effect of Hall conductivity on WGM modes. These results will pave the way for a proof-of-concept demonstration of a millimetre-wave MASER, with potential transferability to other two-dimensional electron systems (GaAs, 2D materials).
Your Work Environment
The PhD will take place at LAAS-CNRS (Toulouse), within the team specializing in microwave and millimetre-wave circuits, under the supervision of Hervé Aubert (LAAS) et Alexei Chepelianskii (LPS). It is part of the ANR HELIQUANT project (48 months, coordinated by LPS), a consortium bringing together LAAS, LPS, FAST, and UTINAM. The PhD candidate will have access to LAAS's microwave characterization and electromagnetic simulation (HFSS) platforms, as well as regular mobility to meet with consortium partners.
Compensation and benefits
Compensation
2300 € gross monthly
Annual leave and RTT
44 jours
Remote Working practice and compensation
Pratique et indemnisation du TT
Transport
Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€
About the offer
| Offer reference | UPR8001-HERAUB-004 |
|---|---|
| CN Section(s) / Research Area | Mathematics and mathematical interactions |
About the CNRS
The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.
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