Quantum computers, systems that process information leveraging quantum mechanical effects, have the potential of outperforming classical systems on some tasks. Instead of storing information as bits, like classical computers, they rely on so-called qubits, units of information that can simultaneously exist in superpositions of 0 and 1.

Researchers at University Paris-Saclay, the Chinese University of Hong Kong and other institutes have developed a new quantum computing platform that utilizes the intrinsic angular momentum (i.e., spin) of nuclei in tungsten-183 (¹⁸³W) atoms as qubits.

Their proposed system, introduced in a paper published in Nature Physics, was found to achieve long coherence times and is compatible with existing superconductor-based quantum information processing platforms.

“For decades, magnetic resonance—NMR and ESR—has been a workhorse of physics, chemistry and biology,” Emmanuel Flurin, senior author of the paper, told Phys.org.

“It was also one of the first platforms used to demonstrate basic quantum computing protocols. However, in its traditional form, it is intrinsically macroscopic: the signals are so weak that one typically needs ensembles of order 10¹⁵ atoms or more just to detect something.”

As part of their study, Flurin and his colleagues set out to improve the sensitivity of magnetic resonance-based quantum computing platforms to observe physical processes down to the single-atom level, all while retaining their quantum coherence. To achieve this, they combined magnetic resonance with superconducting materials, which are known to be highly responsive to electromagnetic signals.

“The main objective of the paper was to show that this combination effectively realizes a quantum version of magnetic resonance,” said Flurin.

“Specifically, we can detect, control and entangle individual nuclear spins in a solid, with coherence times of several seconds, in a chip-scale device that is compatible with microwave quantum technologies.”

A hybrid nuclear-electron spin platform

The quantum information processing system introduced by this team of researchers could be seen as an ultra-sensitive and quantum mechanics-driven version of a magnetic resonance spectrometer, which was built using superconducting circuits. The qubits that the system relies on are nuclear pins of ¹⁸³W atoms within a calcium tungstate CaWO₄ crystal.

“Each of these nuclei sits close to a rare-earth ion, Er³⁺, which carries an unpaired electron spin,” explained Flurin. “The electron spin is much easier to manipulate and detect than the nuclear spin, so it acts as an ancilla or amplifier for the nuclear spin.”

The researchers placed the CaWO₄ crystal on top of a superconducting microwave resonator, a device that stores microwave photons (i.e., particles of light) and that can be used to manipulate quantum states. This resonator was previously patterned direction on a chip. The team subsequently placed the entire device in a so-called dilution refrigerator and cooled it down to a few millikelvin.

“The resonator, combined with a very sensitive microwave detector, makes the setup sensitive enough that the tiny magnetic signal of a single electron spin—and, through it, of a single nuclear spin—becomes measurable,” said Flurin.

“A crucial aspect is that our method only relies on the magnetic resonance properties of the spins. We do not require any additional optical transition (as in NV centers) or particular electrical properties (as in semiconductor donors). This means that, in principle, all the species and techniques developed over decades in NMR and ESR can be directly imported into this platform.”

The team’s newly introduced quantum computing platform has several advantages over previously introduced magnetic resonance-driven systems. Most notably, the researchers were able to improve their system’s magnetic resonance sensitivity by many orders of magnitude, down to the level of single nuclear spins.

“We attained very long coherence times, of the order of seconds, because the qubits are nuclear spins,” said Flurin. “We also developed a general and adaptable method that does not rely on special optical or electrical tricks. Notably, our all-microwave, chip-based architecture is naturally compatible with existing superconducting quantum processors.”

Initial assessment of the team’s system

To assess the potential of their proposed platform, the researchers realized a prototype system and characterized the coherence of two individual nuclear spins in their system.

Ultimately, they demonstrated high-fidelity and single-shot readout, while also implementing microwave-driven single- and two-qubit gates between the two nuclear spins.

“First, we show that one can effectively do NMR/ESR at the single-spin level in a solid-state device,” said Flurin. “We demonstrate individual nuclear spin qubits with coherence times of several seconds, which brings the extraordinary stability of NMR into a fully microscopic, single-qubit regime.”

In their paper, Flurin and his colleagues also introduced a new readout technique that is highly sensitive and non-invasive (i.e., that does not disrupt the system). Coupling the spin of electrons in Er³⁺ atoms to a superconducting resonator and employing a quantum-limited microwave detector, they were able to perform single-shot, quantum non-demolition measurements of each nuclear spin.

“Because this readout is purely magnetic, it is in principle applicable to a broad range of spin species, without relying on optical fluorescence or transport measurements,” explained Flurin.

“We also showed that this platform satisfies the usual requirements for quantum computing. Using only microwave signals, we implement single- and two-qubit gates between nuclear spins and create a long-lived Bell state whose coherence exceeds one second.”

The results of this recent study further highlight the potential of quantum information processing platforms that rely on nuclear spins. The researchers were able to use the nuclear spins of atoms in a solid as fully-fledged qubits, which was not achieved in earlier NMR-related quantum computing experiments relying on large ensembles and pseudo-pure states.

Future applications and research directions

This recent study could soon open new possibilities for the development of quantum technologies, including both quantum computing systems and sensing devices.

“On the one hand, future studies could explore a sensing and spectroscopy route, where this device becomes a kind of quantum magnetic resonance microscope, capable in principle of probing individual molecules and resolving their structure with very high spectral resolution,” said Flurin.

“As we look at individual spins instead of large ensembles, we are not limited by the ‘blurring’ that occurs when many slightly different environments are averaged together. On the other hand, we are pursuing the quantum computing route.”

The researchers showed that long-lived nuclear spins can be highly stable qubits in chip-based quantum computing architectures. As part of their ongoing studies, they are working on an architecture consisting of several small nuclei clusters that can store quantum data. Each of these clusters is coupled to a single electron spin ancilla.

“This ancilla both provides single-shot readout of its local nuclear cluster and acts as a link between neighboring clusters by exchanging microwave photons,” said Flurin. “What we have demonstrated here is the elementary operation of one such cluster: coherent control, second long entanglement and high-fidelity readout of a small set of nuclear spins.”

In their next studies, Flurin and his colleagues plan to take further steps toward the development of quantum sensing and computing systems that build on their recently introduced platform. In the context of sensing, their hope is to successfully use their system to probe individual molecules and more complex systems.

“At the single-spin level, one can in principle access much sharper spectral features than in conventional NMR, where ensemble averaging and inhomogeneous broadening tend to wash out fine details,” explained Flurin. “This could enable a form of single-molecule magnetic resonance spectroscopy with quantum-limited resolution.”

The second goal of the team’s future studies will be to develop increasingly advanced quantum computing systems that leverage their design. To do this, they will try to continuously increase the number of controllable spins in their system and boost gate fidelities.

“With coherence times in the second range and gate times in the millisecond range, there is a lot of room to optimize device design and control protocols, and to start implementing small quantum algorithms or simple error-correcting codes using nuclear spin registers,” said Flurin.

Importantly, the platform introduced by the researchers is driven solely by magnetic resonance and does not rely on specific optical or electrical properties of materials.

Flurin and his colleagues eventually plan to also explore the potential of other types of spins and materials for the realization of their system. In addition, they will try to utilize nuclear spin qubits as long-lived memories or registers in larger superconducting-circuit architectures.

“An important conceptual point for us is that there is a strong synergy between quantum computing and quantum sensing in this platform,” added Flurin.

“A sophisticated magnetic resonance experiment can be viewed as a quantum circuit: each pulse sequence corresponds to a sequence of quantum gates, and the measured spectrum is the output of a quantum algorithm that encodes structural information about the molecule. Our approach makes this connection explicit at the single-spin level.

“This means that advances in quantum computing—for instance in optimal control or error mitigation—can directly benefit next-generation molecular spectroscopy, and, conversely, that the very rich toolbox of NMR and ESR can inspire new ways of processing quantum information.”

© 2025 Science X Network

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The university, where Higgs was emeritus professor, said he died Monday following a short illness.

Higgs predicted the existence of a new particle, which came to be known as the Higgs boson, in 1964. He theorized that there must be a sub-atomic particle of certain dimension that would explain how other particles—and therefore all the stars and planets in the universe—acquired mass. Without something like this particle, the set of equations physicists use to describe the world, known as the standard model, would not hold together.

Higgs’ work helps scientists understand one of the most fundamental riddles of the universe: how the Big Bang created something out of nothing 13.8 billion years ago. Without mass from the Higgs, particles could not clump together into the matter we interact with every day.

But it would be almost 50 years before the particle’s existence could be confirmed. In 2012, in one of the biggest breakthroughs in physics in decades, scientists at CERN, the European Organization for Nuclear Research, announced that they had finally found a Higgs boson using the Large Hardron Collider, the $10 billion atom smasher in a 17-mile (27-kilometer) tunnel under the Swiss-French border.

The collider was designed in large part to find Higgs’ particle. It produces collisions with extraordinarily high energies in order to mimic some of the conditions that were present in the trillionths of seconds after the Big Bang.

Higgs won the 2013 Nobel Prize in Physics for his work, alongside Francois Englert of Belgium, who independently came up with the same theory.

Edinburgh University Vice Chancellor Peter Mathieson said Higgs, who was born in Newcastle, was “a remarkable individual—a truly gifted scientist whose vision and imagination have enriched our knowledge of the world that surrounds us.”

“His pioneering work has motivated thousands of scientists, and his legacy will continue to inspire many more for generations to come.”

Born in Newcastle, northeast England on May 29, 1929, Higgs studied at King’s College, University of London, and was awarded a Ph.D. in 1954. He spent much of his career at Edinburgh, becoming the Personal Chair of Theoretical Physics at the Scottish university in 1980. He retired in 1996.

One highlight of Higgs’ career came in the 2013 presentation at CERN in Geneva where scientists presented in complex terms—based on statistical analysis unfathomable to most laypeople—that the boson had been confirmed. He broke into tears, wiping down his glasses in the stands of a CERN lecture hall.

“There was an emotion—a kind of vibration—going around in the auditorium,” Fabiola Gianotti, the CERN director-general told The Associated Press. “That was just a unique moment, a unique experience in a professional life.”

“Peter was a very touching person. He was so sweet, so warm at the same time. And so always interested in what other people had to say,” she said. “Able to listen to other people … open, and interesting, and interested.”

Joel Goldstein, of the School of Physics at the University of Bristol, said, “Peter Higgs was a quiet and modest man, who never seemed comfortable with the fame he achieved even though this work underpins the entire modern theoretical framework of particle physics.”

Gianotti recalled how Higgs often bristled at the term “God particle” for his discovery: “I don’t think he liked this kind of definition,” she said. “It was not in his style.”

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The reason behind why students hate online classes is that they get distracted easily and turn their attention away from studying. There are countless distractions that can interrupt a student.

Students have their cell phones and computers in their hands for online classes and just one notification can divert them from their classes.

Family members often intervene during online classes which disrupts the rhythm of the child. Students are more relaxed in their home environment. They do not focus properly. They are not as serious as they are in schools.

Classmates and friends talk to each other during online classes and do not concentrate on what is being taught. There is no fear of the teacher which makes the student concentrate on studies.

Students have to be extremely focused to succeed in an online class. They have to concentrate with all their might. They have to be self-disciplined.

No Teacher/Student Contact

Teachers are the main reason why students study properly. They do everything in helping their student learn and achieve the best grade possible.

In online classes, this is not present. Teachers are solely focused on the curriculum. They do not interact with the students and understand their stance on education. The look of disappointment on the teacher’s face when you do not complete your homework or you fail a test is the ultimate wake-up call to do better next time. The famous teacher’s quote, “See me after class” cannot be achieved during online classes.

Teachers give many pieces of advice to their students and it changes their lives and outlook on education. This advice cannot be as heartfelt through online classes.

In physical classes, teachers ask questions from those students who are academically challenged but in online classes, teachers do not ask as many questions as they should.

Computer/Network Problems

Online classes are already not easy to take but with network issues or computer problems, you will inevitably fail. Sometimes, your laptop is not fully charged and you lose valuable minutes finding your charger and hooking it up.

Computers are just not reliable. Just before starting your class, your computer screen can freeze up or an impromptu update can arrive which has to be installed at that very moment.

The internet connection can be a bit slow and the whole class will carry on while you are stuck at loading. The internet connection of your teacher can also be weak which will result in undistinguishable voices and understanding that will be very difficult. Their PowerPoint presentation can fail to show up clearly and the result will be pretty distorted.

The school can send you invalid links to your classes and you lose the start of the lecture by calling the school office for the correct link.

Around 20% of parents in the United States have claimed that they do not have the necessary requirements, such as reliable internet connectivity and multiple computers, to ensure that all their children can access online education.

Teachers Are Not Trained for Online Education

We all know that teachers and school staff are giving their all to make online education just as same as physical on-campus education. They are trying to adapt to this new form of teaching in this short amount of time. We all appreciate their efforts but we can agree on one thing, the quality of education and learning is just not the same.

Teachers are not accustomed to teaching students through online classes. Only some are experts in online teaching, while others try their best.

Most teachers face difficulties writing complicated equations quickly on the computer screens, they are not used to the software which enables them to write these equations.

There Is No Socializing

Socializing is the only thing that cannot be achieved through online classes. Those moments, those jokes, those mementos with friends can only happen on campus. There is no recess, no break, no hanging out with friends and classmates.

You cannot make new friends through online classes. You can talk about schoolwork and stuff but it is not the same. You cannot spend your day of online classes in the same manner as you did in your school.

There is just studying going on in online classes. Students are basically homeschooled at this point.

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Akasaki was born in Chiran, Japan, on 30 January 1929 and graduated from Kyoto University in 1952. After receiving a PhD in electronics in 1964 from Nagoya University, he moved to Matsushita Research Institute Tokyo before returning to Nagoya in 1981 where he remained for the rest of his career. From 1992, Akasaki held a joint position with Meijo University, which is also in Nagoya.

It was at Nagoya and Meijo where Akasaki conduced much of his Nobel-prize-winning research. The first red LED was created in the early 1960s and researchers then managed to create devices that emitted light at ever-shorter wavelengths, reaching green by the end of that decade. However, creating devices that could deliver enough blue light was a struggle. But doing so was essential for a source of white light – needing, as it would, red, green and blue LEDs.

Crystal maze

At Nagoya in the 1980s, Akasaki and Amano focussed on making blue LEDs from the compound semiconductor gallium nitride (GaN) given that it has a large band-gap energy corresponding to ultraviolet light. Yet they needed to overcome several challenges, including the ability to create high-quality crystals of GaN with good optical properties. To do so they used metalorganic vapour phase epitaxy techniques to deposit thin films of high-quality GaN crystals onto substrates.

Another issue was to learn how to dope the GaN so it is a “p-type” semiconductor, which is crucial for creating an LED. Akasaki and Amano noticed, however, that when GaN doped with zinc is placed in an electron microscope, it gives off more light than if undoped, which suggested that electron irradiation improved the p-doping.

This effect was later explained by Nakamura, who was based at the Nichia Corporation and was working independently on GaN blue LEDs. In the early 1990s, both groups then used their high-quality, p-doped GaN to make high-brightness blue LEDs, achieved by combining them with other GaN-based semi-conductors in multilayer “hetero-junction” structures. Today, GaN-based LEDs are used in back-illuminated liquid-crystal displays in devices ranging from mobile phones to TV screens.

In 2014, Akasaki, along with Amano and Nakamura, were awarded the Nobel Prize for Physics for “the invention of efficient blue light-emitting diodes [LEDs] which has enabled bright and energy-saving white light sources”. Akasaki was awarded many other prizes during his career including the Japanese Order of Culture in 2011 and the Queen Elizabeth Prize for Engineering in 2021. He died on 1 April from pneumonia.

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Physicists have been looking for laws that explain both the microscopic world of elementary particles and the macroscopic world of the universe and the Big Bang at its beginning, expecting that such fundamental laws should have symmetry in all circumstances. However, last year, two physicists found a theoretical proof that, at the most fundamental level, nature does not respect symmetry.

How did they do it? Gravity and hologram

There are four fundamental forces in the physical world: electromagnetism, strong force, weak force, and gravity. Gravity is the only force still unexplainable at the quantum level. Its effects on big objects, such as planets or stars, are relatively easy to see, but things get complicated when one tries to understand gravity in the small world of elementary particles.

To try to understand gravity on the quantum level, Hirosi Ooguri, the director of the Kavli Institute for the Physics and Mathematics of the Universe in Tokyo, and Daniel Harlow, an assistant professor at the Massachusetts Institute of Technology, started with the holographic principle. This principle explains three-dimensional phenomena influenced by gravity on a two-dimensional flat space that is not influenced by gravity. This is not a real representation of our universe, but it is close enough to help researchers study its basic aspects.

The pair then showed how quantum error correcting codes, which explain how three-dimensional gravitational phenomena pop out from two dimensions, like holograms, are not compatible with any symmetry; meaning such symmetry cannot be possible in quantum gravity.

They published their conclusion in 2019, garnering high praise from journal editors and significant media attention. But how did such an idea come to be?

It started well over four years ago, when Ooguri came across a paper about holography and its relation to quantum error correcting codes by Harlow, who was then a post doc at Harvard University. Soon after, the two met at the Institute for Advanced Study in Princeton when Ooguri was there on sabbatical and Harlow came to give a seminar.

“I went to his seminar prepared with questions,” Ooguri says. “We discussed a lot afterwards, and then we started thinking maybe this idea he had can be used to explain one of the fundamental properties of quantum gravity, about the lack of symmetry.”

New research collaborations and ideas are often born from such conversations, says Ooguri, who is also a professor at the California Institute of Technology in the U.S.. Ooguri travels at least once a fortnight to give lectures, attend conferences, workshops and other events. While some might wonder if all that travel detracts from concentrating on research, Ooguri believes quite the opposite.

“Scientific progress is serendipitous,” he says. “It often happens in a way that you don’t expect. That kind of development is still very hard to achieve by remote exchange.

“Yes, nowadays it’s easier with e-mails and video conferences,” he continues, “but when you write an e-mail you have to have something to write about. When someone is in the same building, I can walk across the hallway and ask silly questions.”

These silly questions are key to progress in fundamental sciences. Unlike other fields, such as applied science where researchers work towards a specific goal, the first question or idea a theoretical physicist comes up with is usually not the right one, Ooguri says. But, through discussion, other researchers ask questions derived from their curiosity, taking the research in a new direction, landing on a very interesting question, which has an even more interesting answer.

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Quantum technology, which harnesses the strange rules that govern particles at the atomic level, is normally thought of as much too delicate to coexist with the electronics we use every day in phones, laptops and cars. However, scientists with the University of Chicago’s Pritzker School of Molecular Engineering announced a significant breakthrough: Quantum states can be integrated and controlled in commonly used electronic devices made from silicon carbide.

“The ability to create and control high-performance quantum bits in commercial electronics was a surprise,” said lead investigator David Awschalom, the Liew Family Professor in Molecular Engineering at UChicago and a pioneer in quantum technology. “These discoveries have changed the way we think about developing quantum technologies—perhaps we can find a way to use today’s electronics to build quantum devices.”

In two papers published in Science and Science Advances, Awschalom’s group demonstrated they could electrically control quantum states embedded in silicon carbide. The breakthrough could offer a means to more easily design and build quantum electronics—in contrast to using exotic materials scientists usually need to use for quantum experiments, such as superconducting metals, levitated atoms or diamonds.

These quantum states in silicon carbide have the added benefit of emitting single particles of light with a wavelength near the telecommunications band. “This makes them well suited to long-distance transmission through the same fiber-optic network that already transports 90 percent of all international data worldwide,” said Awschalom, senior scientist at Argonne National Laboratory and director of the Chicago Quantum Exchange.

Moreover, these light particles can gain exciting new properties when combined with existing electronics. For example, in the Science Advances paper, the team was able to create what Awschalom called a “quantum FM radio;” in the same way music is transmitted to your car radio, quantum information can be sent over extremely long distances.

“All the theory suggests that in order to achieve good quantum control in a material, it should be pure and free of fluctuating fields,” said graduate student Kevin Miao, first author on the paper. “Our results suggest that with proper design, a device can not only mitigate those impurities, but also create additional forms of control that previously were not possible.”

In the Science paper, they describe a second breakthrough that addresses a very common problem in quantum technology: noise.

“Impurities are common in all semiconductor devices, and at the quantum level, these impurities can scramble the quantum information by creating a noisy electrical environment,” said graduate student Chris Anderson, a co-first author on the paper. “This is a near-universal problem for quantum technologies.”

But, by using one of the basic elements of electronics—the diode, a one-way switch for electrons—the team discovered another unexpected result: The quantum signal suddenly became free of noise and was almost perfectly stable.

“In our experiments we need to use lasers, which unfortunately jostle the electrons around. It’s like a game of musical chairs with electrons; when the light goes out everything stops, but in a different configuration,” said graduate student Alexandre Bourassa, the other co-first author on the paper. “The problem is that this random configuration of electrons affects our quantum state. But we found that applying electric fields removes the electrons from the system and makes it much more stable.”

By integrating the strange physics of quantum mechanics with well-developed classical semiconductor technology, Awschalom and his group are paving the way for the coming quantum technology revolution.

“This work brings us one step closer to the realization of systems capable of storing and distributing quantum information across the world’s fiber-optic networks,” Awschalom said. “Such quantum networks would bring about a novel class of technologies allowing for the creation of unhackable communication channels, the teleportation of single electron states and the realization of a quantum internet.”

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Artificial intelligence and machine learning algorithms are routinely used to predict our purchasing behavior and to recognize our faces or handwriting. In scientific research, Artificial Intelligence is establishing itself as a crucial tool for scientific discovery.

In chemistry, AI has become instrumental in predicting the outcomes of experiments or simulations of quantum systems. To achieve this, AI needs to be able to systematically incorporate the fundamental laws of physics.

An interdisciplinary team of chemists, physicists, and computer scientists led by the University of Warwick, and including the Technical University of Berlin, and the University of Luxembourg have developed a deep machine learning algorithm that can predict the quantum states of molecules, so-called wave functions, which determine all properties of molecules.

The AI achieves this by learning to solve fundamental equations of quantum mechanics, as shown in their paper “Unifying machine learning and quantum chemistry with a deep neural network for molecular wavefunctions,” published in Nature Communications.

Solving these equations in the conventional way requires massive high-performance computing resources (months of computing time) which is typically the bottleneck to the computational design of new purpose-built molecules for medical and industrial applications. The newly developed AI algorithm can supply accurate predictions within seconds on a laptop or mobile phone.

Dr. Reinhard Maurer from the Department of Chemistry at the University of Warwick says, “This has been a joint three year effort, which required computer science know-how to develop an artificial intelligence algorithm flexible enough to capture the shape and behavior of wave functions, but also chemistry and physics know-how to process and represent quantum chemical data in a form that is manageable for the algorithm.”

The team came together during an interdisciplinary three-month fellowship program at IPAM (UCLA) on the subject of machine learning in quantum physics.

Prof Dr. Klaus Robert-Muller from the Institute of Software Engineering and Theoretical Computer Science at the Technical University of Berlin says, “This interdisciplinary work is an important progress as it shows that, AI methods can efficiently perform the most difficult aspects of quantum molecular simulations. Within the next few years, AI methods will establish themselves as essential part of the discovery process in computational chemistry and molecular physics.”

Professor Dr. Alexandre Tkatchenko from the Department of Physics and Materials Research at the University of Luxembourg says, “This work enables a new level of compound design where both electronic and structural properties of a molecule can be tuned simultaneously to achieve desired application criteria.”

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Doctoral student Alexander Hartung became a father twice during the construction of the apparatus. The device, which is three meters long and 2.5 meters high, contains approximately as many parts as an automobile. It sits in the experiment hall of the Physics building on Riedberg Campus, surrounded by an opaque, black tent inside which is an extremely high performing laser. Its photons collide with individual argon atoms in the apparatus, and thereby remove one electron from each of the atoms. The momentum of these electrons at the time of their appearance is measured with extreme precision in a long tube of the apparatus.

The device is a further development of the COLTRIMS (Collision Optical Laser Testing Reaction Interacting Momentum System) principle that was invented in Frankfurt and has meanwhile spread across the world: it consists of ionising individual atoms, or breaking up molecules, and then precisely determining the momentum of the particles. However, the transfer of the photon momentum to electrons predicted by theoretic calculations is so tiny that it was previously not possible to measure it. And this is why Hartung built the “super COLTRIMS.”

When numerous photons from a laser pulse bombard an argon atom, they ionise it. Breaking up the atom partially consumes the photon’s energy. The remaining energy is transferred to the released electron. The question of which reaction partner (electron or atom nucleus) conserves the momentum of the photon has occupied physicists for over 30 years. “The simplest idea is this: as long as the electron is attached to the nucleus, the momentum is transferred to the heavier particle, i.e., the atom nucleus. As soon as it breaks free, the photon momentum is transferred to the electron,” explains Hartung’s supervisor, Professor Reinhard Dörner from the Institute for Nuclear Physics. This would be analogous to wind transferring its momentum to the sail of a boat. As long as the sail is firmly attached, the wind’s momentum propels the boat forward. The instant the ropes tear, however, the wind’s momentum is transferred to the sail alone.

However, the answer that Hartung discovered through his experiment is—as is typical for quantum mechanics—more surprising. The electron not only receives the expected momentum, but additionally one third of the photon momentum that actually should have gone to the atom nucleus. The sail of the boat therefore “knows” of the impending accident before the cords tear and steals a bit of the boat’s momentum. To explain the result more precisely, Hartung uses the concept of light as an electro-magnetic wave: “We know that the electrons tunnel through a small energy barrier. In doing so, they are pulled away from the nucleus by the strong electric field of the laser, while the magnetic field transfers this additional momentum to the electrons.”

Hartung used a clever measuring setup for the experiment. To ensure that the small additional momentum of the electron was not caused accidentally by an asymmetry in the apparatus, he had the laser pulse hit the gas from two sides: either from the right or the left, and then from both directions simultaneously, which was the biggest challenge for the measuring technique. This new method of precision measurement promises deeper understanding of the previously unexplored role of the magnetic components of laser light in atomic physics.

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