Physics/Mathematics/Computer Science

As machine learning is seeping into all strata of modern societies, it is increasingly used to automate decisions or draw conclusions. However, myriads of recent examples have revealed patent discrimination: Flickr’s and Google Photos’ image labeling in 2015 [1], recidivism risk assessment with COMPAS in 2016 [2], Amazon’s job application review in 2018 [3], Twitter’s image cropping in 2020 [4], DALL-E image generator in 2021 [5], etc. All displayed strong ethnic or gender biases.

Multi-petawatt laser facilities, such as Apollon in Paris, will generate very high light intensities to explore novel strong-field frontiers in plasma- and laboratory astrophysics. Relativistic plasma mirrors represent a promising technology to significantly boost the peak laser intensity by utilizing highly nonlinear light-plasma interactions that happen at the mirror surface. The objective of my research is to numerically simulate these laser-plasma interactions to understand how they impact the maximum laser intensities that can be achieved.

When a very intense laser collides with a highly energetic electron beam, gamma rays are emitted.

Intense sources of high-energy gamma-ray photon beams are of great interest for scientific endeavors in fundamental and applied sciences such as probing the limits of the Standard Model of particle physics, as well as for applications in industry, medicine, and material science. However, existing photon sources are extremely limited in photon intensity at these high energies.

Electric propulsion for satellites is a technology that largely reduces the launch costs and provides reliable orbit control capabilities. Nevertheless, the design and development of plasmas thrusters is still semi-empirical and involves long and expensive life tests due to the complex, nonlinear physics of low-temperature plasmas, making its study an active field of research. In this project I will be collaborating with Prof. Ken Hara to develop innovative models and numerical methods to study the onset of plasma instabilities in magnetized configurations.

Spatial audio refers to various systems and techniques used to diffuse sound sources or sound fields in space. While “surround sound” systems which are present in many homes typically involve 5 to 7 speakers, more advanced techniques such as Ambisonics and Wave Field Synthesis (WFS) imply the use of a much greater number of speakers. Those techniques are very efficient to recreate sound spatialization and are of high interest in fields like virtual and augmented reality, acoustic of concert room, archeoacoustics, etc.

Low-temperature plasmas have multiple vital scientific and industrial applications, including plasma processing, electric propulsion, arc discharges, and many more. Plasmas exhibit complex phenomena in a wide range of both spatial and temporal scales, spanning frequencies from gigahertz to kilohertz and length scales from microns to meters.

A major health challenge our societies are about to face on the long-term is cancer, as it is already the primary cause of death in France and the second one in the US. As a way to tackle it, one of the most used techniques nowadays is radiotherapy. It uses high-dose radiations to kill cancer cells detected with medical imaging. Yet, as cancer can be located in sensitive areas, and in a bid to protect surrounding healthy tissues, radiations must be precise and directional.

The physics of ionized gases, or plasmas, gives rise to a great variety of fascinating phenomena like northern lights or solar flares. In particular, plasmas are widely used in technologies, ranging from the fabrication of microelectronic chips and the production of thin films to satellite propulsion.

The interaction of highly energetic particles with plasmas plays a major role in the evolution of the universe and gives rise to many astrophysical processes that are not yet fully understood. Our collaboration, consisting of groups from France and the USA, aims at creating these processes within a laboratory, which permits a high degree of control and insight into parameters that are otherwise not accessible.