The physicist who built the ultrafast "attosecond" laser won the Nobel Prize

Pierre Agostini, Ferenc Krausz, and Anne L'Huillier won the award for their ultra short optical pulses, which made close research on electrons possible.

Ferenc Klaus, Anne Lullier, and Pierre Agostini (from left to right)

Image sources: BBVA Foundation, Kenneth Ruona/Lund University, Ohio State University
This year's Nobel Prize in Physics was awarded to three physicists - Pierre Agostini of Ohio State University in Columbus, Ferenc Klaus of the Max Planck Institute for Quantum Optics in Germany, and Anne Rullier of Lund University in Sweden - for their research on attosecond light pulses.

Asecond physics enables scientists to observe the smallest particles on the shortest time scale. The winners have developed methods for generating these ultrafast laser pulses, which can be used to study our world at the smallest scale and have been applied in chemistry, biology, and physics.

The Royal Swedish Academy of Sciences in Stockholm announced the award this morning. The winner shares a prize of 11 million Swedish krona (1 million US dollars).

The winners include the fifth woman to win the Physics Prize. Among the 221 previous winners, only 4 were women: Marie Curie won the award in 1903 for her work on radiation phenomena; In 1963, Maria Goeppert Mayer won the award for uncovering some details of atomic structure; In 2018, Donna Strickland won an award for her work in laser physics; Andrea Ghez won the award in 2018. In 2020, it was used to study supermassive black holes.

When Anne Lullier received the phone call to learn that she had won, she was teaching. The last half hour of my speech was very difficult, "she said at the press conference after the awards. As you know, not many women have won this award, so it is very special
The ability to generate attosecond light has opened the door to the electronic world on a very small time scale, "said Eva Olsen, Chairman of the Nobel Committee on Physics, at a press conference As early as 1925, Werner Heisenberg believed that the world was invisible. Thanks to attosecond physics, this situation is now beginning to change.

Mauro Nisoli, an electrical engineer at the Polytechnic University of Milan in Italy who studies the science of the second, said that the choice of the winner made him "very happy". Marc Vrakking, a researcher at the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy in Berlin, Germany, added that the winners are "well deserved". One by one, they have made significant contributions to this field, "Fragin and other experts learned of today's news at the Asecond Science Conference held in Barcelona, Spain. From that moment on, no one could truly listen to the conversation
To Vladimir's surprise, the committee chose to reward only experimental physicists. He said that without the significant contributions of theorists, this field would never have developed into what it is now.

Asecond Science
Objects that move too fast to be photographed will generate a light band image during photography. But using an extremely fast strobe light to illuminate an object can make it appear as if it has been frozen by time. The working principle of attosecond light pulses is the same, opening up a phenomenon world that was once considered impossible to see.

The story of atomic science began in the late 1980s, when L'Huillier and her collaborators at a research institute (later part of the University of Sartre in Paris) were studying ionized argon. When they expose the gas to infrared lasers, it generates a series of higher frequency photons, which means that the individual particles emitted by argon gas have higher energy than the particles in the laser that triggers them. All of these frequencies are overtones of lasers - like repeating the same notes on a piano, but with higher frequencies.

L'Huillier and other researchers, including physicist Paul Corkum, who was working at the Canadian National Research Council in Ottawa at the time, quickly elucidated the physical principles behind how gases produce these "high order harmonics". This led to the discovery of a phenomenon called heavy collisions. When a laser wave impacts an atom, the electric field of the wave will tear apart electrons, leaving positive ions behind. But if the frequency of the wave is correct, its rapidly oscillating field will immediately reverse direction and push the electron back to the ion before it has time to go elsewhere. The incoming electrons usually have more energy than is required for the initial ionization of atoms, and the additional energy is released in the form of high-frequency photons.

Realizing that these higher frequencies could be used to generate extremely short pulses, L'Huiller began a plan to increase the intensity of higher-order harmonics. In 2001, a team led by Pierre Agostini of the University of Sartre in Paris successfully converted high-order harmonics into attosecond pulses. It is crucial that Agostini developed a technique to measure the duration of pulses and confirm that they are in an attosecond state - something that has never been done before.

Laser focusing
At first, the attosecond pulses were too close to each other to be useful. In order to use them to study attosecond processes, researchers need to isolate pulses. Achieving this goal requires starting with a very short laser pulse, up to several thousand attoseconds. In the late 1990s, with the contribution of the Nisoli team, Krausz developed a technique for generating short isolated pulses. In a 2001 experiment, Klaus combined his laser with a high-order harmonic generator to generate pulses lasting only 650 attoseconds, breaking through the 1000 attosecond barrier for the first time. He was the only person in the early days who possessed laser technology and could conduct attosecond science in your ideal way, "said Vladimir Putin.

In the following years, Klaus' team and others utilized this technology to conduct a series of groundbreaking attosecond scientific experiments. Researchers measured the speed of the photoelectric effect, where light removes electrons from atoms. Physicists know that this is a complex process and assume that electrons will not be released immediately, but there is no way to measure their actual duration until attosecond science becomes possible.

Soon, these technologies were not only applied to individual atoms, but also to molecules, even solids and liquids. An attosecond pulse can reveal what happens immediately after a molecule loses electrons and ionizes: the remaining electrons begin to rearrange, "long before the nucleus realizes anything is happening," Nisoli said. Researchers are currently working to extend this technology to "atomic chemistry": they plan to use light pulses to guide bond formation and fracture in a way that does not occur spontaneously.
The motivation behind this research is very fundamental - can we create short pulses and what can we do with it? 'L'Huillier said at a press conference. We need time to start seeing applications in medicine, semiconductor industry, and chemistry.

Source: OFweek