Description du sujet de thèse

The doctoral candidate (M/F) will work within an experimental and theoretical project aimed at studying the Casimir-Polder (C-P) interaction. The goal of this project is to gain a deeper understanding of how the geometry of nanostructures influences the C-P potential, as well as the effects of modifying this interaction with a classical laser field.

Quantum vacuum fluctuations are characterized by the spontaneous creation and annihilation of virtual photons occurring continuously. In particular, the presence of macroscopic surfaces influences these fluctuations, leading to a spatially varying Lamb shift. The gradient of this shift generates an attractive force known as the Casimir-Polder force. This force between an atom and a surface is dominant at the nanometric scale and plays a crucial role across many areas of physics, such as atomic physics, biophysics, and physico-chemistry. Understanding this force is therefore essential for exploring new physics involving atoms and materials, including, for example, the investigation of the hypothetical fifth force.

The activity will take place within the Laser Physics Laboratory, a joint research unit of the University Sorbonne Paris Nord and the CNRS. The Atomic Optics and Interferometry group (OIA, see https://www.lpl.univ-paris13.fr/recherche/optique-et-interferometrie-atomiques-oia) has developed an interferometric approach in which a laser-cooled atomic wave packet diffracts on a nanostructure. The phase shift of the wave packet induced by the C-P interaction significantly alters the diffraction pattern. The main objective of the PhD is to develop a comprehensive understanding of this interaction based on the diffraction patterns. First, the research will focus on the hypothetical existence of the fifth force, which is a hypothetical short-range gravitational-like force that could be screened by the presence of the Casimir-Polder forces. Additionally, the project will explore the control of these forces through the modulation of nanostructure geometry or the application of laser fields.

The future student will participate in various aspects of the experiment, such as improving the experimental setup, data acquisition and analysis, designing new nanostructures, and more. Simultaneously, he/she will contribute to the theoretical aspect of the project, including quantum electrodynamics calculations, modeling diffraction patterns, FDTD simulations, etc. The candidates (M/F) should be highly motivated by experimental physics (lasers, optical setups, data collection and analysis using simple software) and theoretical physics (performing numerical simulations). They should possess strong physics knowledge, be motivated, and capable of working effectively within a team

Contexte de travail

This doctoral project will be conducted at the Laser Physics Laboratory, a joint research unit of Sorbonne Paris Nord University and the CNRS, within the Atomic Optics and Interferometry team (OIA group; see https://www.lpl.univ-paris13.fr/recherche/optique-et-interferometrie-atomiques-oia). It is part of the ANR LIGRINT project. The team comprises a CNRS researcher, a professor, a maître de conférence, and a doctoral student. In parallel, the team has established collaborations with several theoretical groups, including the University of Leibniz in Hanover, LPTMS/ISMO in Orsay, Kassel, and others.

Contraintes et risques

Laser and electrical hazards.