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Category: particle physics

Overcoming symmetry limits in photovoltaics through surface engineering

A recent study carried out by researchers from EHU, the Materials Physics Center, nanoGUNE, and DIPC introduces a novel approach to solar energy conversion and spintronics. The work tackles a long-standing limitation in the bulk photovoltaic effect—the need for non-centrosymmetric crystals—by demonstrating that even perfectly symmetric materials can generate significant photocurrents through engineered surface electronic states. This discovery opens new pathways for designing efficient light-to-electricity conversion systems and ultrafast spintronic devices.

The work is published in the journal Physical Review Letters.

Conventional solar cells rely on carefully engineered interfaces, such as p–n junctions, to turn light into electricity. A more exotic mechanism—the bulk photovoltaic effect —can generate electrical current directly in a material without such junctions, but only if its crystal structure lacks inversion symmetry. This strict requirement has long restricted the search for practical materials.

Wormholes may not exist—we’ve found they reveal something deeper about time and the universe

Wormholes are often imagined as tunnels through space or time—shortcuts across the universe. But this image rests on a misunderstanding of work by physicists Albert Einstein and Nathan Rosen.

In 1935, while studying the behavior of particles in regions of extreme gravity, Einstein and Rosen introduced what they called a “bridge”: a mathematical link between two perfectly symmetrical copies of spacetime. It was not intended as a passage for travel, but as a way to maintain consistency between gravity and quantum physics. Only later did Einstein–Rosen bridges become associated with wormholes, despite having little to do with the original idea.

But in new research published in Classical and Quantum Gravity, my colleagues and I show that the original Einstein–Rosen bridge points to something far stranger—and more fundamental—than a wormhole.

Slowing down muon decay with short laser pulses

Muons are unstable subatomic particles that spontaneously and rapidly transform into other particles via a process known as electroweak decay. Altering the speed with which muons decay into other particles was so far deemed a challenging quest, requiring very strong electromagnetic fields that cannot be produced in conventional laboratory settings.

Researchers at the University of Plymouth, however, explored the possibility of influencing muon decay using short laser pulses. Their paper, published in Physical Review Letters, suggests that the behavior of muons can be altered when they pass through laser beams, an effect that could, in principle, also be achieved using laboratory lasers.

“Records are regularly being set for the highest intensity electromagnetic fields we can produce in the lab,” Dr. Ben King, co-author and Associate Professor of Theoretical Physics at the University of Plymouth, told Phys.org.

Hidden magma oceans could shield rocky exoplanets from harmful radiation

Deep beneath the surface of distant exoplanets known as super-Earths, oceans of molten rock may be doing something extraordinary: powering magnetic fields strong enough to shield entire planets from dangerous cosmic radiation and other harmful high-energy particles.

Earth’s magnetic field is generated by movement in its liquid iron outer core—a process known as a dynamo—but larger rocky worlds like super-Earths might have solid or fully liquid cores that cannot produce magnetic fields in the same way.

In a paper published in Nature Astronomy, University of Rochester researchers, including Miki Nakajima, an associate professor in the Department of Earth and Environmental Sciences, report an alternative source: a deep layer of molten rock called a basal magma ocean (BMO). The findings could reshape how scientists think about planetary interiors and have implications for the habitability of planets beyond our solar system.

New spectroscopic method reveals ion’s complex nuclear structure

Different atoms and ions possess characteristic energy levels. Like a fingerprint, they are unique for each species. Among them, the atomic ion 173 Yb+ has attracted growing interest because of its particularly rich energy structure, which is promising for applications in quantum technologies and searches for so-called new physics. On the flip side, the complex structure that makes 173 Yb+ interesting has long prevented detailed investigations of this ion.

Now, researchers from PTB, TU Braunschweig, and the University of Delaware have taken a closer look at the ion’s energy structure. To achieve this, they trapped a single 173 Yb+ ion and developed methods for preparing and detecting its energy state despite the complicated energy structure. This enabled high-resolution laser and microwave spectroscopy. The research is published in the journal Physical Review Letters.

In particular, the researchers investigated energy shifts arising from interactions between the nucleus and its surrounding electrons, also called hyperfine structure. Combined with first-principle theory calculations, the precise measurement results yielded new information about the ion’s nucleus.

What Is Nanotechnology? The Atomic Future Waiting to Begin

The idea never died, progress is still being made.

Nanotechnology was once imagined as the next great technological revolution—atom-by-atom manufacturing, machines as small as cells, and materials we can only dream of today. Instead, it stalled. While AI, robotics, and nuclear surged ahead, nanotech faded into the background, reduced to buzzwords and sci-fi aesthetics.

But the idea never died.

We can manipulate matter at the atomic scale. We can design perfect materials. We can build molecular machines. What’s been missing isn’t physics—it’s ambition, investment, and the will to push beyond today’s tools.

In this interview with futurist J. Storrs Hall, we explore what nanotechnology really is, why it drifted off course, and why its future may finally be on the horizon. If AI was a “blue-sky fantasy” until suddenly it wasn’t, what happens when someone decides nanotech deserves the same surge of talent, money, and imagination?

Continue reading “What Is Nanotechnology? The Atomic Future Waiting to Begin” | >

An Accordion Lattice Playing a Soliton Tune

Decades after their experimental realization, wave patterns known as discrete solitons continue to fascinate.

Localized wave patterns in a lattice or other periodic media have been observed using arrays of coupled torsion pendula, chains of Josephson junctions, and arrays of optical waveguides. Joining this diverse repertoire is a recent experiment by Robbie Cruickshank of the University of Strathclyde in the UK and his collaborators [1]. Starting from a Bose-Einstein condensate (BEC) of cesium atoms, the researchers used an ingenious combination of experimental methods to realize, visualize, and theoretically explore coherent wave structures known as discrete solitons. These nonlinear waveforms have long been theorized to exist, and their implications have been extensively studied. In my view, Cruickshank and company’s experiment constitutes the clearest manifestation of discrete solitons so far achieved in ultracold atomic systems, paving the way for a variety of future explorations.

Solitons are localized wave packets that emerge from the interplay of dispersion and nonlinearity. Dispersion tends to make wave packets spread, and nonlinearity tends to localize them. The interplay can be robust and balanced, resulting in long-lived structures. The presence of a lattice introduces a new dimensional unit, the lattice constant, to the interplay, enabling a potential competition between the lattice constant and the scale of the soliton. When the latter is much larger than the former, the soliton is effectively insensitive to the lattice, which it experiences as a continuum. But as the two scales approach one another, lattice effects become more pronounced, and the associated waveforms become discrete solitons. In nonlinear variants of the Schrödinger equation, discreteness typically favors standing waves rather than traveling ones. That’s because the lattice-induced energy barrier known as the Peierls-Nabarro barrier makes discrete solitons less mobile.

New state of matter discovered in a quantum material

At TU Wien, researchers have discovered a state in a quantum material that had previously been considered impossible. The definition of topological states should be generalized.

The work is published in Nature Physics.

Quantum physics tells us that particles behave like waves and, therefore, their position in space is unknown. Yet in many situations, it still works remarkably well to think of particles in a classical way—as tiny objects that move from place to place with a certain velocity.

Neutral-atom arrays, a rapidly emerging quantum computing platform, get a boost from researchers

For quantum computers to outperform their classical counterparts, they need more quantum bits, or qubits. State-of-the-art quantum computers have around 1,000 qubits. Columbia physicists Sebastian Will and Nanfang Yu have their sights set much higher.

“We are laying critical groundwork to enable quantum computers with more than 100,000 qubits,” Will said.

In a paper published in Nature, Will, Yu, and their colleagues combine two powerful technologies— optical tweezers and metasurfaces—to dramatically scale the size of neutral-atom arrays.

Atomic-level surface control boosts brightness of eco-friendly nanosemiconductors by 18-fold

Light-emitting semiconductors are used throughout everyday life in TVs, smartphones, and lighting. However, many technical barriers remain in developing environmentally friendly semiconductor materials.

In particular, nanoscale semiconductors that are tens of thousands of times smaller than the width of a human hair (about 100,000 nanometers) are theoretically capable of emitting bright light, yet in practice have suffered from extremely weak emission. KAIST researchers have now developed a new surface-control technology that overcomes this limitation.

A KAIST research team led by Professor Himchan Cho of the Department of Materials Science and Engineering has developed a fundamental technology to control, at the atomic level, the surface of indium phosphide (InP) magic-sized clusters (MSCs)—nanoscale semiconductor particles regarded as next-generation eco-friendly semiconductor materials.

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