The 2023 Nobel Prize in Physics goes to research that opened the doors to the world of electrons – 10/03/2023 – Science

The 2023 Nobel Prize in Physics goes to a trio of researchers who discovered how to use extremely fast pulses of light to study the behavior of electrons, particles of matter on which much of 21st century technologies depend.

French-American Pierre Agostini, from Ohio State University (USA), Hungarian-Austrian Ferenc Krausz, from the Max Planck Institute for Quantum Optics, and Frenchwoman Anne L’Huillier, from Lund University (Sweden), will equally share the prize of 11 million Swedish kronor (just under US$1 million). L’Huillier is the fifth woman to win the physics prize in the 122-year history of the Nobel Prize.

“I wasn’t sure if I was dreaming or if it was reality,” said Krausz when contacted by the Nobel committee to comment on the award. Regarding his discoveries regarding the movement of electrons, he stated: “It’s always exciting to see something that no one had been able to see before. It was an incredible moment that I will never forget.”

The three researchers work with so-called attosecond physics. An attosecond is equivalent to one quintillionth of a second, or 1 second times 10^-18.

At the presentation of the award, to make it clear how small this scale is, researcher Eva Olsson, member of the Nobel Prize in Physics Selection Committee, lined up little flags on the table with the number 1,000 written on them. By dividing a second by 1,000 six times in a row, we arrive at the attosecond, explained Olsson. There are as many attoseconds within a single second as there are seconds that have passed since the origin of the Universe, almost 14 billion years ago.

The emission of light pulses on this time scale makes it possible to measure the displacement of electrons that occurs, for example, in the so-called photoelectric effect. In this phenomenon, particles of light (photons) that strike a material can lead to the emission of electrons from that material.

The ability to measure this and other processes with high precision could bring important applications in areas such as electronics, catalyst development and medicine.

The Nobel committee at the Royal Swedish Academy of Sciences also specified the contribution of each of the laureates to research in the field. According to the commission, the first seminal work was that of Anne L’Huillier, who, in 1986, studied the interaction of light from an infrared laser with noble gases (that is, gases that tend not to form molecules with other chemical elements).

The big problem for physicists who sought to directly examine what happened to atoms and fundamental particles of matter can be compared to the lack of a ruler of the right size to measure these phenomena. The tremendous speed of electron movement, for example, is greater than the propagation speed of light waves, which usually have a defined length — more or less like the peaks that separate waves at sea, for example.

In her work, however, the French researcher showed the possibility of using the laser to produce “sub-waves” thanks to the interaction of light with electrons in the gas. To understand how this works, you can think of the sound waves of a musical instrument.

When someone plays a note on a piano, for example, the sound emitted is a mixture of the “official” note of that key — a “C” or a “D”, say — and a series of sounds with a frequency higher than that of the note, so-called overtones. It is the mixture of overtones that makes the same note on a guitar or piano sound different to our ears, because it is specific to each instrument.

The French researcher’s work investigated the presence of analogues of these musical overtones when electrons from noble gases interacted with the laser. The light caused electrons to acquire energy and temporarily leave the vicinity of their atoms. When the direction of the light changed, the electrons returned to their atoms and, to do so, emitted energy in the form of pulses of ultraviolet light, which corresponded to different overtones of the original light.

This principle was used experimentally by the other winners, Agostini and Krausz, in 2001. They discovered how to better control the luminous overtones, so that they reinforced each other, increasing their intensity. Agostini worked with consecutive pulses of light, 250 attoseconds long, while Krausz analyzed isolated pulses of 650 attoseconds. Current research has already lowered this limit to a few tens of attoseconds.

As a result, it becomes increasingly viable to use such pulses of light as “microscopes” to monitor the behavior of individual atoms and electrons. It is a tool with potential impact for the creation of electronic devices and even for medicine, through detailed analysis of the structure of the organism’s molecules, for example.

Recent history of the Nobel Prize in Physics

The 2022 prize went to three laureates: Alain Aspect, John F. Clauser and Anton Zeilinger, for their research in quantum physics and the applications their discoveries could have for new technologies.

In 2021, the award went to the study of complex systems, including those that allow understanding the climate changes that affect our planet. The winners were Syukuro Manabe, from the United States, and Klaus Hasselmann, from Germany, for modeling the Earth’s climate and making predictions about global warming. Another half of the prize went to Giorgio Parisi, from Italy, who revealed hidden patterns in disordered complex materials, from atomic to planetary scales, in an essential contribution to the theory of complex systems, with relevance also for the study of climate.

The discovery of black holes and their impact on understanding the Universe won the 2020 Nobel Prize in Physics. The award was shared between Roger Penrose, Reihard Genzel and Andrea Ghez.

The prize

Since 1901, 116 Nobel Prizes in Physics have been awarded to 221 people.

The award began due to the death of Swedish chemist Alfred Nobel (1833-1896), inventor of dynamite and responsible for the development of rubber and synthetic leather. The scientist registered, in total, 355 patents throughout his life.

In his last will dated 1895, Nobel recorded that his fortune should be allocated to the construction of a prize — which was received by his family with protest. After six years, Nobel’s wish was finally fulfilled and the first prize was awarded.

Indications

The evaluation process for a Nobel Prize in Physics begins in September of the year before the prize is awarded. The first stage consists of sending approximately 3,000 invitations to nominate names that could be recognized by the honor. Guests cannot nominate themselves.

These invitations are addressed to members of the Royal Swedish Academy of Sciences, members of the Nobel Physics Committee, Nobel Prize winners in Physics, physics professors at universities and institutes of technology in Sweden, Denmark, Finland, Iceland and Norway, and the Institute Karolinska, in Stockholm and other scientists that the Academy considers suitable to receive the invitations.

The institution also invites professors from at least six universities around the world. Typically, invitations are extended to more academic centers with the aim of ensuring adequate distribution of nominations across continents and areas of knowledge.

Then, the hundreds of names selected are analyzed using processes, such as developing reports, to narrow the selection. Finally, in October, the Academy, by majority vote, decides who will receive recognition.