Nobel Prize in Physics recognizes three scientists’ work with fast-pulsed lasers

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Three scientists whose work with rapidly pulsing lasers has produced the fastest measurements known to humankind are the latest recipients of the Nobel Prize in Physics.

Pierre Agostini of Ohio State University in the United States, Ferenc Krausz of the Max Planck Institute of Quantum Optics in Garching, Germany, and Anne L’Huillier of Lund University in Sweden were all named co-winners of the physic prize by the Royal Swedish Academy of Sciences on Tuesday.

All three are being recognized for their pioneering work in attosecond science – a specialty involving phenomena that are so brief they last only billionths of billionths of a second.

To achieve such a fleeting snapshot of the natural world, scientists have developed lasers capable of producing intense but incredibly brief pulses of light, a technology that was long in the making but only came to fruition starting around 2001.

Applications of the field include observing and even manipulating the motions of electrons within molecules to probe a range of processes in chemistry and materials science.

“I’m so happy to get this prize,” said Dr. L’Huillier, who learned she had won the Nobel while she was teaching a class and was later dialed into a press briefing to announce the winners. “You know, there are not so many women who have got this prize, so it’s very, very special.”

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Dr. L’Huillier is only the fifth woman to receive the physics Nobel – the third in the past five years, including Donna Strickland of the University of Waterloo, who won in 2018, also for work related to laser physics.

For Canadian researchers who work in the field, Tuesday’s announcement comes with some disappointment because it excludes Paul Corkum, a University of Ottawa professor and laser physicist whose long running career with National Research Council Canada helped lay the groundwork for attosecond science.

Prior the announcement, Dr. Corkum had been considered one of Canada’s top contenders for a Nobel. Last year he was named a co-winner of the Wolf Prize in physics together with Dr. Krausz and Dr. L’Huillier. That award, granted annually by the Israel-based Wolf Foundation, is sometimes described as second only to the Nobel in prestige and significance.

Both prizes underscore the impressive series of breakthroughs by multiple research teams that led to the development of attosecond science over the past 35 years.

They include a 1988 finding by Dr. L’Huillier and several colleagues that atoms of the so-called rare gases, such as xenon, krypton and argon, can be stimulated by an infrared laser to emit light at related but higher frequencies, like higher pitch harmonics on a musical instrument. By 1991, Dr. L’Huiller and a different set of co-authors, including Kenneth Kulander of Lawrence Livermore National Laboratory in California, had arrived at a mathematical description of the phenomenon.

In 1993, Dr. Corkum, who was studying the effect at the NRC, published a way to view how the harmonics were produced. In this view, they originated as electrons were alternately ripped away and then slammed back toward their atoms by waves of laser light. The energy the electrons gained in the process would then be released in the form of higher frequency light.

The following year, he and Dr. L’Huillier, together with others, produced a fully developed theory of the effect.

At the same time, Dr. Agostini, who was then based at the Saclay Nuclear Research Centre near Paris, showed how the duration of the laser pulses could be measured. More progress followed as all three of this year’s physics laureates as well as Dr. Corkum added to what had become a rapidly advancing field.

Then, in 2001, both Dr. Agostini and Dr. Kraucz – who was based at the University of Vienna – set important milestones by respectively generating trains and isolated pulses of laser light at attosecond timescales.

The discovery of harmonics had given rise to a new tool. And like a camera system with a high speed shutter, it has paved the way for observing extremely short term events on the scale of electrons moving around within atoms and molecules.

It’s this access that explains why the field is being recognized with a Nobel, said André Staudte, who leads the NRC’s attosecond science group.

Whereas physics of the 20th century was based on a static picture of matter, he said, “Real life is non-static. Molecules change. Chemical reactions happen. All of this is fundamentally driven by electronic transitions, because electrons move and atoms re-arrange.”

He added that the group continues to do both fundamental and applied research in the field, including looking for ways of producing rapid pulsing lasers with materials that are more easily handled and practical than rare gasses.

The Nobel Prize in Physics was first awarded to German scientist Wilhelm Rontgen in 1901 for his discovery of X-rays. Other celebrated winners include Marie Curie (1903), Albert Einstein (1921) and Enrico Fermi (1938).

No Canadian claimed the prize until 1990, when Richard E. Taylor, a Stanford University professor, was named a co-winner for work that helped verify that the protons and neutrons that make up the nuclei of all atoms are made of smaller point-like particles called quarks.

Since then, another five Canadians have won, most recently Jim Peebles, a Manitoba native and Princeton University cosmologist who became a Nobel laureate in 2019.