The 2023 Nobel Prize in Physics has been awarded to three researchers for their contributions to attosecond science. The prize honors Pierre Agostini of the Ohio State University, Ferenc Krausz of the Max Planck Institute of Quantum Optics, and Anne L’Huillier of Lund University. The trio is being recognized for developing “experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter.” The scientists will each receive one-third of the prize money—11 million Swedish kronor (about $1 million).
Tracking molecular scale events, such as vibrations and the making and breaking of chemical bonds, requires ultrafast detection technology. Researchers developed some of those femtosecond (10-15 sec) methods in the 1990s. But the laser pulses that drive those methods aren’t quick enough to track the speedy motions of electrons. That feat requires even shorter light pulses—in the range of attoseconds (10-18 sec), just a billionth of a billionth of a second. Attosecond laser techniques made their debut in the early 2000s, and it is that work and the field’s pioneers being honored with this year’s Physics prize.
Why probe the motions of electrons on the attosecond time scale? As Eva Olsson, a physicist at Chalmers University of Technology and a member of the Nobel physics committee explained at the Nobel Prize press conference today in Stockholm, by tracking electrons in real time, scientists can address fundamental properties of materials, such as the time scale of the photoelectric effect. Proposed by Einstein in 1905, that process describes the events that lead to electron emission from materials when they are irradiated.
Attosecond technology can also be used to study the basics of chemistry. For example, the techniques have been used to trace the shape of electron orbitals and to study electron-transfer processes in molecules. Electron- and charge-transfer steps are often the molecular scale events that kick off redox reactions and other chemical processes.
At the press conference, Mats Larsson, a physicist at Stockholm University and also a member of the prize committee, offered other examples of attosecond applications. He noted that these light pulses can instantaneously boost the electrical conductivity of a dielectric material 18 orders of magnitude. That process abruptly switches insulators to conductors, opening the door to ultrafast electronics.
Attosecond science is even making headway into medicine, Larsson said. The techniques are being used to record molecular fingerprints of compounds in blood samples. That work may eventually lead to methods that recognize subtle differences between samples and detect molecular markers for cancer at the earliest stages of the disease.
Marc Vrakking, a professor of ultrashort physics at the Free University of Berlin, says today’s prize is "recognition of the pioneering insights of the field.” He says all three laureates deserve the award but he notes that unfortunately other scientists who contributed to attosecond science cannot also be recognized, including those who developed the theoretical underpinnings of the experimental work the prize recognizes.
L’Huillier, one of this year’s laureates, was teaching when the Nobel Committee tried calling her. She finally took the call after the third or fourth attempt to reach her. She said she was so excited by the news that it was difficult to finish her lecture.
“This is the most prestigious prize and I am so happy to get [it],” she said. “It’s incredible. As you know, there are not so many women that get this prize. So it’s very, very special.”
This story was updated on Oct. 3 to provide quotes from Eva Olsson, Mats Larsson, Marc Vrakking and Anne L’Huillier, as well as more detail about the laureates’ prize-winning work.