On Tuesday, three scientists were awarded the Nobel Prize in Physics for providing the first split-second view into the speedy world of spinning electrons, a realm that could one day lead to improved electronics or disease diagnosis.
The prize was given to French-Swedish physicist Anne L’Huillier, French scientist Pierre Agostini, and Hungarian-born Ferenc Krausz for their work on the little component of each atom that races about the center and is crucial to almost everything: chemistry, physics, our bodies, and our electronics.
Electrons travel so rapidly that human efforts to isolate them have failed, but by gazing at the smallest fraction of a second possible, scientists now have a “blurry” view of them, which experts say opens up whole new sciences.
“The electrons are very fast, and the electrons are really the workforce in everywhere,” stated Nobel Committee member Mats Larsson. “Once you can control and understand electrons, you have taken a very big step forward.”
L’Huillier, of Sweden’s Lund University, is the fifth woman to receive the Nobel Prize in Physics.
“I say to all the women, if you’re interested, if you have a little bit of passion for these types of challenges, just go for it,” L’Huillier told The Associated Press.
What Physics Discovery Won the Nobel Prize?
Separately, the scientists employed ever-faster laser pulses to capture the atomic motion that occurred at such dizzying speeds—one quintillionth of a second, known as an attosecond—much like photographers use rapid shutters to capture a hummingbird eating.
How Small Is That?
“Let’s take one second, which is the time of a heartbeat,” Nobel Committee head Eva Olsson stated. That would have to be divided by 1,000 six times to achieve the realm of the attosecond.
According to Nobel Committee member physicist Mark Pearce, “there are as many attoseconds in a second as there are seconds since the Big Bang, 13.8 billion years ago.”
Even when scientists “see” the electron, they can only see so much of it.
“You can see whether it’s on one side of a molecule or the other,” L’Huillier, 65, explained. “It’s still very blurry.”
“The electrons are much more like waves, like water waves, than particles and what we try to measure with our technique is the position of the crest of the waves,” she stated.
Why Are Electrons Important?
Electrons are important because they are “how the atoms bind together,” according to L’Huillier. It is the site of chemical reactions.
“Electrons are, even if we can’t see them, omnipresent in our life—our biological life and also our technical life, in our everyday life,” Krausz stated during a press conference. “In our biological life, electrons form the adhesive between atoms, with which they form molecules and these molecules are then the smallest functional building stones of every living organism.”
And if you want to understand how they work, you must first understand how they move, according to Krausz.
This study is currently concerned with comprehending our cosmos, but it is hoped that it will someday have numerous practical uses in electronics, illness diagnosis, and fundamental chemistry.
L’Huillier, on the other hand, believes her work demonstrates the importance of working on fundamental science regardless of future applications because she worked on it for 30 years before potential real-world applications became apparent.
What Were the Reactions of Anne L’Huillier, Ferenc Krausz, and Pierre Agostini?
L’Huillier was teaching basic engineering physics to roughly 100 undergraduates at Lund when she received the phone call informing her that she had won, but her phone was on quiet and she did not answer. During a break, she examined it and called the Nobel Committee.
She then returned to teaching.
“I was very concentrated, forgot about the Nobel Prize, and tried to finish my lecture,” L’Huillier explained to the Associated Press. She left class early to attend the news conference announcing the prize at the Royal Swedish Academy of Sciences in Stockholm.
“This is the most prestigious award, and I am overjoyed to have received it.” “It’s incredible,” she said during the press conference. “As you know there are not so many women who got this prize so it’s very special.”
The Nobel Foundation shared a photo of L’Huillier putting a phone to her ear on social media.
“Dedicated teacher alert!” exclaimed the post on X, formerly Twitter. “Not even the 2023 #NobelPrize in Physics could tear Anne L’Huillier from her students.”
And L’Huillier said she wasn’t authorized to tell the pupils what happened because the award was a mystery at the time, although she did say they suspected.
Agostini, an emeritus professor at Ohio State University, was in Paris and could not be reached by the Nobel Committee before the award was revealed publicly.
Krausz, of the Max Planck Institute for Quantum Optics and the Ludwig Maximilian University of Munich, expressed surprise to reporters.
“I have been trying to figure out since 11 a.m. … whether I’m in reality or it’s just a long dream,” claimed the 61-year-old.
“I thought I’d try it and then it became clear that I can’t hang up so quickly this time,” Krausz said of the phone call from the Nobel committee.
Krausz and L’Huillier shared the coveted Wolf prize in physics last year with University of Ottawa physicist Paul Corkum. Nobel prizes are limited to three recipients, and Krausz expressed regret that Corkum was not among them.
“I haven’t received a phone call from the committee.” Maybe it’s not true. “I don’t know,” he laughed to the AP. “I think the committee is looking for me in Columbus.”
“There are certainly younger people who would have appreciated it far more than me,” the 82-year-old jokingly said. “It’s good but it is a bit late for me.”
“I don’t think I would have deserved it more earlier!” he added.
Corkum was critical in measuring the split-second laser bursts, according to Krausz.
The Nobel Prizes are endowed with a financial prize of 11 million Swedish kronor ($1 million) left by the prize’s originator, Swedish inventor Alfred Nobel.
The physics award comes just one day after two scientists were awarded the Nobel Prize in medicine for discoveries that enabled the development of COVID-19 mRNA vaccines.
The Nobel Committee Announcement:
The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics 2023 to
Pierre Agostini
The Ohio State University, Columbus, U.S.
Ferenc Krausz
Max Planck Institute of Quantum Optics, Garching and Ludwig-Maximilians-Universität München, Germany
Anne L’Huillier
Lund University, Sweden
“for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter”
Light Experiments Capture the Tiniest of Moments
The three Nobel Laureates in Physics 2023 are being honored for their experiments that have provided humanity with new instruments for investigating the world of electrons inside atoms and molecules. Pierre Agostini, Ferenc Krausz, and Anne L’Huillier demonstrated a method for producing extremely short light pulses that can be used to examine the quick processes by which electrons migrate or change energy.
When humans perceive fast-moving events, they flow into each other, much as a video made up of motionless images is regarded as continuous movement. Special technology is required to analyze extremely short events. Change happens in the world of electrons in a few tenths of an attosecond—an attosecond is so short that there are as many in one second as there have been seconds since the universe’s origin.
The laureates’ investigations created light pulses as brief as attoseconds, proving that these pulses can be utilized to offer images of activities inside atoms and molecules.
Anne L’Huillier discovered many different light overtones in 1987 when she passed infrared laser light through a noble gas. Each overtone is a light wave with a predetermined number of cycles for each cycle of laser light. They are created by laser light interacting with atoms in the gas, which provides extra energy to some electrons, which is subsequently emitted as light. Anne L’Huillier has continued to investigate this phenomenon, laying the groundwork for future discoveries.
Pierre Agostini succeeded in creating and studying a series of continuous light pulses lasting only 250 attoseconds in 2001. Simultaneously, Ferenc Krausz was working on another type of experiment, one that allowed him to isolate a single light pulse lasting 650 attoseconds.
The contributions of the laureates have permitted the exploration of processes that were before difficult to track.
“We can now enter the world of electrons.” Attosecond physics allows us to better comprehend mechanisms governed by electrons. “The next step will be to put them to use,” says Eva Olsson, Chair of the Nobel Committee for Physics.
Many diverse fields have possible applications. It is critical in electronics, for example, to understand and control how electrons behave in a material. Attosecond pulses can also be utilized in medical diagnostics to distinguish distinct substances.
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Electrons in Pulses of Light
This year’s laureates have developed fashes of light that are brief enough to capture images of electrons’ very fast motions. Anne L’Huillier identified a new phenomena caused by the interaction of laser light with atoms in a gas. Pierre Agostini and Ferenc Krausz demonstrated how to harness this effect to generate shorter light pulses than were previously achievable.
A hummingbird’s wings can beat up to 80 times per second. We can only hear a whirring sound and see a hazy movement. Rapid movements blur together for the human senses, and extremely short events are impossible to see. We must use technical methods to capture or show these fleeting moments.
Footing phenomena can be captured in detail thanks to high-speed photography and strobe lighting. A finely focused shot of a hummingbird in flight necessitates a significantly shorter exposure period than a single wingbeat.
The faster the occurrence, the faster the photograph must be taken in order to capture the moment.
The same idea applies to all methods used to measure or represent rapid processes; any measurement must be performed faster than the time it takes for the system being studied to undergo a significant change, or the result will be ambiguous. This year’s laureates demonstrated a method for producing light pulses that are brief enough to capture photographs of events inside atoms and molecules.
The natural time scale of atoms is extremely small. Atoms in a molecule can move and turn in millionths of a billionth of a second, known as femtoseconds. These movements can be investigated using the shortest laser pulses—but when complete atoms move, the timeframe is governed by their huge and heavy nuclei, which are extraordinarily slow compared to light and nimble electrons.
Electrons move so swiftly inside atoms or molecules that changes are blurred in a femtosecond. Positions and energies change at speeds ranging from one to a few hundred attoseconds, where an attosecond is one billionth of a billionth of a second.
An attosecond is so short that the number of them in one second equals the number of seconds since the cosmos began to exist, 13.8 billion years ago. On a more human scale, consider sending a flash of light from one end of a room to the opposite wall—this takes 10 billion attoseconds.
A femtosecond was long thought to be the limit for the amount of light that could be produced.
Improving existing equipment was insufficient to see events taking place on the incredibly short periods of electrons; something altogether new was required. This year’s laureates carried out experiments that helped to establish the new research field of attosecond physics.
Shorter Pulses Made Possible With High Overtones
Light is made up of waves, which are vibrations in electrical and magnetic fields that move faster than anything else in a vacuum. Different wavelengths correspond to different colors. Red light, for example, has a wavelength of roughly 700 nanometres, or one hundredth the breadth of a hair, and it cycles at about 430,000 billion times every second. The shortest feasible pulse of light can be thought of as the length of a single period in the light wave, the cycle in which it swings up to a peak, down to a trough, and back to its starting position.
Because the wavelengths employed in common laser systems can never fall below a femtosecond, this was viewed as a hard limit for the shortest feasible bursts of light in the 1980s.
The mathematics that defines waves shows that any wave form can be produced with enough waves of the correct sizes, wavelengths, and amplitudes (distances between peaks and troughs). The trick with attosecond pulses is that they may be made shorter by mixing more and shorter wavelengths.
Observing electron movements on an atomic scale necessitates the use of short enough light pulses, which involves combining short waves of several different wavelengths.
More than simply a laser is required to add new wavelengths to light; the key to reaching the briefest second yet examined is a phenomena that occurs when laser light passes through a gas. Light interacts with its atoms, resulting in overtones—waves that complete a number of complete cycles for each cycle in the original wave. This is analogous to the overtones that give a sound its own character, allowing us to distinguish between the identical note played on a guitar and a piano.
Anne L’Huillier and her colleagues at a French laboratory were able to synthesize and show overtones in 1987 by passing an infrared laser beam through a noble gas. Infrared lighting
The laser with shorter wavelengths utilized in prior research produced more and louder overtones. Many overtones with similar light intensity were observed in this experiment.
Throughout the 1990s, L’Huillier continued to investigate this effect in a series of studies, including at her new home, Lund University. Her findings helped to advance theoretical knowledge of this phenomena, providing the groundwork for the next experimental breakthrough.
Escaping Electrons Create Overtones
When laser light penetrates the gas and affects its atoms, electromagnetic vibrations occur that disrupt the electric field that holds the electrons around the atomic nucleus. The electrons are then free to leave the atoms. However, the electrical feld of light vibrates continuously, and when it changes direction, a loose electron may rush back to the nucleus of its atom. The electron absorbed a lot of extra energy from the laser light’s electrical feld during its excursion, and in order to rejoin to the nucleus, it must discharge its excess energy as a light pulse. The overtones seen in the experiments are caused by light pulses from electrons.
Light’s energy is proportional to its wavelength. The energy emitted by the overtones is equivalent to ultraviolet light, which has shorter wavelengths than visible light. Because the energy comes from the vibrations of the laser light, the vibration of the overtones will be neatly proportional to the wavelength of the original laser pulse. Different light waves of different wavelengths emerge from light’s interaction with numerous different atoms.
Once these overtones are present, they interact with one another. When the peaks of the lightwaves meet, the light gets more intense, but it becomes less intense when the peak of one cycle coincides with the trough of another. Under the right conditions, the overtones coincide, resulting in a series of pulses of ultraviolet light a few hundred attoseconds long. The theory underpinning this was recognized by physicists in the 1990s, but the breakthrough in actually recognizing and testing the pulses occurred in 2001.
Pierre Agostini and his French research team were successful in making and studying a succession of consecutive light pulses, similar to a train with cars. They employed a clever approach to see how the overtones were in phase with each other by combining the “pulse train” with a delayed portion of the initial laser pulse. This approach also provided them with a measurement for the duration of the pulses in the train, revealing that each pulse lasted only 250 attoseconds.
Simultaneously, Ferenc Krausz and his Austrian research team were developing a technology that could choose a single pulse—much like a carriage being uncoupled from a train and shifted to another track. The 650 attosecond pulse they were able to isolate was used to track and examine a process in which electrons were dragged away from their atoms.
These investigations proved that attosecond pulses could be detected and measured, as well as utilised in future experiments.
Now that the attosecond world is available, these brief bursts of light can be used to examine electron motion. It is already possible to generate pulses as short as a few dozen attoseconds, and this technology is constantly evolving.
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Electrons’ Movements Have Become Accessible
Attosecond pulses allow researchers to quantify the time it takes to pull an electron away from an atom and investigate how this time varies depending on how strongly the electron is attached to the atom’s nucleus. It is now possible to reconstruct how electron distribution in molecules and materials oscillates from side to side or place to place; earlier, their position could only be measured as an average.
Attosecond pulses can be used to investigate the internal processes of matter and to detect various events. These pulses have been used to investigate the atomic and molecular physics in great detail, and they have potential uses ranging from electronics to medicine.
Attosecond pulses, for example, can be used to push molecules, which emit a detectable signal. The signal from the molecules has a unique structure, a form of fingerprint that tells which molecule it is, and medical diagnostics could be one of the applications.