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Category: particle physics – Page 224

A small team of chemists at the Russian Academy of Sciences, has found that metal atoms, not nanoparticles, play the key role in catalysts used in fine organic synthesis. In the study, reported in the Journal of the American Chemical Society, the group used multiple types of electron microscopy to track a region of a catalyst during a reaction to learn more about how it was proceeding.

Prior research has shown that there are two main methods for studying a reaction. The first is the most basic: As ingredients are added, the reaction is simply observed and/or measured. This can be facilitated through use of high-speed cameras. This approach will not work with nanoscale reactions, of course. In such cases, chemists use a second method: They attempt to capture the state of all the components before and after the reaction and then compare them to learn more about what happened.

This second approach leaves much to be desired, however, as there is no way to prove that the objects under study correspond with one another. In recent years, have been working on a new approach: Following the action of a single particle during the reaction. This new method has proven to have merit but it has limitations as well—it also cannot be used for reactions that occur in the nanoworld. In this new effort, the researchers used multiple types of electron microscopy coupled with .

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Researchers in Germany and the U.S. have shown for the first time that terahertz (THz) light pulses can stabilize ferromagnetism in a crystal at temperatures more than three times its usual transition temperature. As the team reports in Nature, using pulses just hundreds of femtoseconds long (a millionth of a billionth of a second), a ferromagnetic state was induced at high temperature in the rare-earth titanate YTiO3 which persisted for many nanoseconds after the light exposure. Below the equilibrium transition temperature, the laser pulses still strengthened the existing magnetic state, increasing the magnetization up to its theoretical limit.

Using light to control magnetism in solids is a promising platform for future technologies. Today’s computers mainly rely on the flow of electrical charge to process information. Moreover, digital memory storage devices make use of magnetic bits that must be switched external magnetic fields. Both of these aspects limit the speed and energy efficiency of current computing systems. Using light instead to optically switch memory and computing devices could revolutionize processing speeds and efficiency.

YTiO3 is a transition metal oxide that only becomes ferromagnetic, with properties resembling those of a fridge magnet, below 27 K or −246°C. At these low temperatures, the spins of the electrons on the Ti atoms align in a particular direction. It is this collective ordering of the spins which gives the material as a whole a macroscopic magnetization and turns it ferromagnetic. In contrast, at temperatures above 27 K, the individual spins fluctuate randomly so that no ferromagnetism develops.

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Inside a lab, scientists marvel at a strange state that forms when they cool down atoms to nearly absolute zero. Outside their window, trees gather sunlight and turn them into new leaves. The two seem unrelated—but a new study from the University of Chicago suggests that these processes aren’t so different as they might appear on the surface.

The study, published in PRX Energy on April 28, found links at the between photosynthesis and exciton condensates—a strange state of physics that allows energy to flow frictionlessly through a material. The finding is scientifically intriguing and may suggest new ways to think about designing electronics, the authors said.

“As far as we know, these areas have never been connected before, so we found this very compelling and exciting,” said study co-author Prof. David Mazziotti.

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He thinks about Robert Oppenheimer and the Manhattan Project that led to the atomic bomb, Hiroshima, and Nagasaki, and the current state of mutually assured destruction (MAD). It started with a science experiment to split the atom and soon the genie was released from the bottle.

I think of the arrival of generalized AI like ChatGPT as being equivalent to the revolution brought on by the invention of movable type and the printing press. Would the Reformation in Europe have happened without it? Would Europe’s rise to world dominance in the 18th and 19th centuries have resulted? The printing press genie uncorked led to a generalized knowledge revolution with both good and bad consequences.

The future uncorked AI genie with no guidance from us could, in answering the question I asked at the beginning of this posting, see humanity as the greatest threat to life on the planet and act accordingly if we don’t gain control over it.

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Researchers at Caltech have discovered a new phenomenon, “collectively induced transparency” (CIT), where light passes unimpeded through groups of atoms at certain frequencies. This finding could potentially improve quantum memory systems.

A newly discovered phenomenon dubbed “collectively induced transparency” (CIT) causes groups of atoms to abruptly stop reflecting light at specific frequencies.

CIT was discovered by confining ytterbium atoms inside an optical cavity—essentially, a tiny box for light—and blasting them with a laser. Although the laser’s light will bounce off the atoms up to a point, as the frequency of the light is adjusted, a transparency window appears in which the light simply passes through the cavity unimpeded.

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Northeastern researchers have made what they describe as a groundbreaking discovery in the field of quantum mechanics.

Wei-Chi Chiu, a postdoctoral researcher at Northeastern reporting to Arun Bansil, university distinguished professor of physics at Northeastern, tells Northeastern Global News that his team has published a novel study examining the nature of a specific class of subatomic particles, whose very existence has eluded quantum physicists for nearly a century.

Chiu and his colleagues propose a new theoretical framework to explain how these particles, called Weyl fermions, interact with each other in certain materials. The findings, published in Nature Communications earlier this month, look beyond the framework of Albert Einstein’s to probe these mysterious particles, Chiu says.

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Encoding breakthrough allows for solving wider set of applications using neutral-atom quantum computers. QuEra Computing and university researchers have developed a method to expand the optimization calculations possible with neutral-atom quantum computers. This breakthrough, published in PRX Quantum, overcomes hardware limitations, enabling solutions to more complex problems, thus broadening applications in industries like logistics and pharmaceuticals.

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To test this idea, the researchers studied the conditions of the extremely early universe. When our cosmos was very young, it was also small, hot and dense. In that youthful cosmos, all forms of matter and energy were ramped up to unimaginable scales, far greater than even our most powerful particle colliders are capable of achieving.

The researchers found that in this setup, gravitational waves — ripples in the fabric of space-time generated by collisions between the most massive cosmic objects — play an important role. Normally, gravitational waves are exceedingly weak, capable of nudging an atom through a distance less than the width of its own nucleus. But in the early universe, the waves could have been much stronger, and that could have seriously influenced everything else.

Those early waves would have sloshed back and forth, amplifying themselves. Anything else in the universe would have gotten caught up in the push and pull of the waves, leading to a resonance effect. Like a kid pumping their legs at just the right time to send a swing higher and higher, the gravitational waves would have acted as a pump, driving matter into tight clumps over and over again.

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What does quantum computing have in common with the Oscar-winning movie “Everything Everywhere All at Once”? One is a mind-blowing work of fiction, while the other is an emerging frontier in computer science — but both of them deal with rearrangements of particles in superposition that don’t match our usual view of reality.

Fortunately, theoretical physicist Michio Kaku has provided a guidebook to the real-life frontier, titled “Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything.”

“We’re talking about the next generation of computers that are going to replace digital computers,” Kaku says in the latest episode of the Fiction Science podcast. “Today, for example, we don’t use the abacus anymore in Asia. … In the future, we’ll view digital computers like we view the abacus: old-fashioned, obsolete. This is for the garbage can. That’s how the future is going to evolve.”

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