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Diode-Like Behavior Arising from Antiferromagnetism

An antiferromagnet with a zigzag magnetic structure exhibits a diode effect that has potential applications in spintronics.

In a traditional diode, current flows in one direction only, thanks to an internal charge imbalance. Researchers have now shown a diode-like effect in an antiferromagnet with a zigzag magnetic structure [1]. The underlying mechanism is different from that in traditional diodes, as the zigzag pattern creates a combined magnetic and electric field that favors current flow in one direction. The strength of the diode effect in the antiferromagnet is relatively small, but rather than exploiting the effect to make a diode for conventional circuits, the team foresees possible applications in spintronics, devices that make use of electron spins.

A typical diode is a junction between two semiconductors having different charge carriers. The charge imbalance across this junction restricts current to flow in only one direction. Diode-like behavior can, in principle, occur in a single material, but it requires that the material’s internal structure is asymmetric in a particular way. This asymmetry should produce two effects: an internal electric field and an internal magnetic field. When those two fields are perpendicular to each other, they can exert a one-way force—called a toroidal moment—on electrons moving through the material, explains Kenta Sudo from Tohoku University in Japan.

Making sense of quantum gravity in five dimensions

Quantum theory and Einstein’s theory of general relativity are two of the greatest successes in modern physics. Each works extremely well in its own domain: Quantum theory explains how atoms and particles behave, while general relativity describes gravity and the structure of spacetime. However, despite many decades of effort, scientists still do not have a satisfying theory that combines both into one clear picture of reality.

Most common approaches assume that gravity must also be described using quantum ideas. As physicist Richard Feynman once said, “We’re in trouble if we believe in quantum mechanics but don’t quantize gravity.” Yet quantum theory itself has deep unresolved problems. It does not clearly explain how measurements lead to definite outcomes, and it relies on strange ideas that clash with everyday experience, such as objects seemingly behaving like both waves and particles, and apparent nonlocal connections between distant systems.

These puzzles become even sharper because of Bell’s theorem. This theorem shows that no theory based on ordinary ideas—such as locality, an objective reality, and freely chosen measurements—can fully match the predictions of quantum theory within our usual four-dimensional view of space and time. These quantum predictions have been repeatedly confirmed in tests of entanglement, first discussed by Einstein, Podolsky, and Rosen (EPR). As a result, simple classical explanations limited to ordinary four-dimensional spacetime cannot fully account for what we observe.

Betelgeuse’s elusive companion star: Siwarha’s ‘wake’ detected

Using new observations from NASA’s Hubble Space Telescope and ground-based observatories, astronomers have tracked the influence of a recently discovered companion star, Siwarha, on the gas around Betelgeuse. The research, by scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA), reveals a trail of dense gas swirling through Betelgeuse’s vast, extended atmosphere, shedding light on why the giant star’s brightness and atmosphere have changed in strange and unusual ways.

The results of the new study were presented Monday at a news conference at the 247th meeting of the American Astronomical Society in Phoenix. The paper has been accepted for publication in The Astrophysical Journal and is available on the arXiv preprint server.

Fault-tolerant quantum computing: Novel protocol efficiently reduces resource cost

Quantum computers, systems that process information leveraging quantum mechanical effects, could soon outperform classical computers on some complex computational problems. These computers rely on qubits, units of quantum information that share states with each other via a quantum mechanical effect known as entanglement.

Qubits are highly susceptible to noise in their surroundings, which can disrupt their quantum states and lead to computation errors. Quantum engineers have thus been trying to devise effective strategies to achieve fault-tolerant quantum computation, or in other words, to correct errors that arise when quantum computers process information.

Existing approaches work either by reducing the extra number of physical qubits needed per logical qubit (i.e., space overhead) or by reducing the number of physical operations needed to perform a single logical operation (i.e., time overhead). Effectively tackling both these goals together, which would enable more scalable systems and faster computations, has so far proved challenging.

Versatile mechanophore detects structural damage without false alarms from heat or UV

A newly designed robust mechanophore provides early warning against mechanical failure while resisting heat and UV, report researchers from Institute of Science Tokyo. They combined computational chemistry techniques with thermal and photochemical testing to show that their mechanophore scaffold, called DAANAC, stays inert under environmental stress yet emits a clear yellow signal when mechanically activated. This could pave the way for smart, self-reporting materials in construction, transportation, and electronics.

High-performance polymers, such as plastics and elastomers, are essential materials in modern life that are present in everything from airplane parts to bridges and electronics. Because sudden failures in these sectors can be extremely dangerous and costly, ensuring the safety and longevity of high-performance polymers is a critical challenge.

Since damage is often invisible at the molecular level until it is too late, scientists have been actively developing compounds known as “mechanophores.” These molecular sensors, which can be embedded into the bulk of a polymeric material, serve as an early warning system by chemically reacting to mechanical stress and producing visible light via fluorescence or other phenomena.

Protein disposal system may accelerate Alzheimer’s by transferring toxins between brain cells

A research group led by Professor Michael Glickman, dean of Technion’s Faculty of Biology, has uncovered a key mechanism in the development of Alzheimer’s. The mechanism in question identifies toxic proteins and disposes of them.

In most cases, harmful proteins are degraded inside the cell. However, the researchers found that in certain situations, the very system meant to eliminate these proteins simply transfers them outside the cell. This discovery may explain how a disease that begins randomly in individual neurons can spread to large regions of the brain.

The study, published in Proceedings of the National Academy of Sciences, was led by Prof. Glickman and postdoctoral researcher Dr. Ajay Wagh. In their article, they describe how brain cells deal with UBB+1, a defective and toxic variant of the protein ubiquitin.

Discoveries rewrite how some minerals form and dissolve

Two related discoveries detailing nanocrystalline mineral formation and dynamics have broad implications for managing nuclear waste, predicting soil weathering, designing advanced bioproducts and materials and optimizing commercial alumina production.

The two recently published studies combine detailed molecular imaging and molecular modeling to sort out how gibbsite, a common aluminum-containing mineral, forms and dissolves in exquisite detail.

Metal–metal bonded molecule achieves stable spin qubit state, opening path toward quantum computing materials

Researchers at Kumamoto University, in collaboration with colleagues in South Korea and Taiwan, have discovered that a unique cobalt-based molecule with metal–metal bonds can function as a spin quantum bit (spin qubit)—a fundamental unit for future quantum computers. The findings provide a new design strategy for molecular materials used in quantum information technologies.

The study is published in the journal Chemical Communications.

A New UV Laser Sends Messages in Trillionths of a Second

Ultrafast UV-C light just took a leap forward, opening the door to lightning-fast communications and next-generation photonic technologies.

Devices that work with ultraviolet light in the UV-C range (100−280 nm) are becoming increasingly important across many fields, including super-resolution microscopy and optical communications. Scientists are especially interested in UV-C light because it scatters strongly in the atmosphere, a property that makes it useful for non-line-of-sight communication. This means data could be sent even when a clear line of sight is blocked, such as in cluttered or obstructed environments. Despite these advantages, progress has been slow because researchers have lacked practical components that can reliably generate and detect UV-C light.

A new platform for ultrafast UV-C pulses.

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