4 Catching the Electron’s Motion: The Nobel Prize in Physics 2023 for Attosecond Light by Zhi-Yi Wei

On 3rd Oct, 2023, the Nobel Prize in Physics was awarded to Pierre Agostini, Ferenc Krausz, and Anne L’Huillier for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter. It is the fourth Nobel Prize for ultrafast science and technology since Prof. A.H. Zewail became a Nobel laureate for his work on femtosecond chemistry in 1999.

An attosecond is presently the shortest time scale for characterizing dynamics in temporal resolution. Its duration is extremely short; it is only one billionth of a billionth second (10−18 s). Since an electron moves around a nucleus in a time scale of about 150 as, scientists may take a “photograph” of its electron motion. From the perspective of the temporal domain, it has opened a door to explore the dynamics inside atoms with unprecedented resolution and will raise our understanding of the physical world.

Prof. Wei Zhiyi, a leading scientist on ultrafast laser technology at the Institute of Physics of the Chinese Academy of Sciences, was excited to learn that the Nobel Prize was awarded for research in attosecond physics. Prof. Zhiyi said, “The three laureates have all made pioneering contributions to the field of attosecond physics, and their Nobel Prize in Physics is well deserved. It is also an inspiration for scientists and students in the field of ultrafast science.”

The attosecond laser was first demonstrated by the respective groups of Pierre Agostini and Ferenc Krausz in 2001. They both used femtosecond Ti:sapphire lasers to drive noble gases for higher-order harmonic generation (HHG). Pierre Agostini’s experiments succeeded in producing a series of continuous pulses of light in France, each lasting only 250 as. In 2005, he moved to the USA and became a professor of physics at Ohio State University. Ferenc Krauss’s research group produced the world’s first isolated attosecond pulse in Austria, which is a milestone breakthrough that allows humans to observe and record the movement of electrons inside an atomic structure. Ferenc Krausz also made a number of remarkable contributions for the development of cutting-edge ultrafast laser technology.

Prof. Zhiyi stated, “We are working on a similar research field with Prof. Ferenc Krausz’s team and established a collaboration more than ten years ago. He is a quick thinker with smart ideas, can well open and lead the direction of scientific research in ultrafast science and technology. He often was the key person in academic conferences and gave important and fascinating talks.” Up to now, both keep in communication. In June, he and colleagues visited Ferenc Krausz for academic purposes. Just this morning, he received an email from Ferenc Krausz.

The birth of attosecond lasers can be traced back to the discovery of HHG. In 1988, A. L’Huillier and others observed that a HHG spectrum could be produced via intense laser irradiation of atoms. The fifth woman to become a Nobel Laureate in physics, she also made a significant contribution to the development of an appropriate theoretical description of the process and has conducted many pioneering experiments since moving to Sweden.

Regarding domestic research on attosecond physics, Prof. Zhiyi is proud of its development in China. Prof. Zhiyi has been engaged in research on ultrafast laser technology and its applications. In 2013, he and his team achieved an attosecond pulse for the first time in China. Presently, he works as a chief scientist for the construction of an ultrafast laser facility at the Institute of Physics, CAS.

He said, “Although the research generally started late, especially regarding attosecond generation, remarkable progress has been made rapidly in recent years, and some related research in application experiments has reached an international and advanced level. A new attosecond laser facility has been established at our institute.” Prof. Zhiyi believes new development and scientific innovation in the attosecond field may be realized in China in the near future.