High Harmonic Generation in cavity for an attosecond quantum source

Full description

Attophysics is at the forefront of time-resolved spectroscopy. Indeed, it harnesses the shortest light pulse probe that can be produced experimentally, thanks to the high harmonic generation (HHG) process. A standard way to trigger HHG is to submit an atomic system to an oscillating electromagnetic field whose strength compares with the Coulomb potential bounding electrons with their nuclei. This non-linear, non-perturbative optical effect produces a broadband coherent radiation in the extreme ultraviolet (XUV) frequency range, which forms attosecond (10 ¹⁸ s) ⁻pulses. Since its discovery in the late 1980s, continuous experimental and theoretical efforts have been dedicated to get a complete understanding of this complex phenomenon. Despite the tremendous success of attosecond science, there is still no consensus about a quantum description of the process. We foresee that such a description of HHG would push forward our understanding of non-linear optics and open up new perspectives for attosecond science.

The two aspects are apparently incompatible: studying quantum optical effects requires a photon counting regime, while HHG requires a strong field regime. To get around this apparent contradiction, we will induce HHG in a cavity, using a very high repetition rate source. The principle is to coherently superimpose the driving pulses circulating in the cavity and keep the repetition rate of an oscillator, about 50MHz (see Figure and [Pup]). The technique has recently shown its worth by producing the first precise nuclear spectroscopy of Thorium, leading the way towards the development of a nuclear clock [Zha]. This project will be the opportunity to develop the first CE-HHG source in France. A demonstration experiment at low energy is readily available in our lab with a Ti:Sa oscillator.

The intership will be the opportunity for the applicant to acquire strong experimental skills in numerous fields of optics such as optical frequency combs, high harmonic generation and quantum optics. He/she will integrate a very active group and will have the opportunity to visit other reknown labs, in particular in the group of C. Heyl in DESY, Hamburg, who is collaborating in the project. If possible, the applicant is encouraged to visit our lab.

Location

CEA-Saclay, 91 Essonne, France

Internship conditions

• Internship duration: 6 months
• Level of study: Bac+5
• Training: Master 2
• Continuation in PhD thesis: Yes
• Application deadline: 7 octobre 2024

Useful methods and technics:
Extreme-ultraviolet frequency combs for precision metrology and attosecond science
Ioachim Pupeza, Chuankun Zhang, Maximilian Högner and Jun Ye, Nat. Phot. 15, 3 (2021)

Frequency ratio of the 229mTh nuclear isomeric transition and the 87Sr atomic clock,
Chuankun Zhang, Tian Ooi, Jacob S. Higgins, Jack F. Doyle, Lars von der Wense, Kjeld Beeks, Adrian Leitner, Georgy A. Kazakov, Peng Li, Peter G. Thirolf, Thorsten Schumm & Jun Ye, Nature 633, 63-70 (2024)

Supervisor

David Bresteau
Phone: +336 52 62 73 57
Email :