She leads an attosecond physics group which studies the movements of electrons in real time, which is used to understand the chemical reactions on the atomic level.

She carried out her dissertation research at the Commissariat à l'énergie atomique et aux énergies alternatives (CEA), near Paris.

[10] As a post-doctoral student, L'Huillier worked at the Chalmers Institute of Technology in Gothenburg, Sweden, and at the University of Southern California in Los Angeles, United States.

[12] L'Huillier's research involves experimental and theoretical aspects of high harmonic generation in gases, which corresponded to extremely short light pulses in the ultraviolet spectral range, lasting tens or hundreds of attoseconds.

[14] In 1994, Maciej Lewenstein, L’Huiller and Paul Corkum presented a full quantum theory of high harmonic generation.

[5] These attosecond sources are considered the world's fastest cameras, using extremely short pulses of light to measure electrons as they move or change in energy.

[13] In 2010, an experiment led by Ferenc Krausz at the Max Planck Institute of Quantum Optics, highlighted a discrepancy between theory and experimental results concerning photoemission delays in neon atoms.

One year later, in 2019, she was recognized with the Prize for Fundamental Aspects of Quantum Electronics and Optics, announced by the European Physical Society.

"[21] In October 2023, she was awarded the Nobel Prize in Physics, jointly with Krausz and Pierre Agostini for "for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter".