Neutrinos ‘flavor’ may hold clues to the universe’s biggest secrets

Inside the Super-Kamiokande detector.
Photo Credit: Kamioka Observatory, ICRR (Institute for Cosmic Ray Research), The University of Tokyo.

In a new analysis, physicists provide the most precise picture yet of how neutrinos change ‘flavor’ as they travel through the cosmos. 

Neutrinos are fundamental particles of the universe, but also some of the most elusive; They pass through everything and can be extremely difficult to detect. While many of their properties are mysterious, scientists know neutrinos come in three types: electron, muon, and tau. 

Understanding these different identities can help scientists learn more about neutrino masses and answer key questions about the evolution of the universe, including why matter came to dominate over antimatter in the early universe, said Zoya Vallari, 

Exotic roto-crystals

Spontaneous fragmentation of a rotating crystal comprised of transversely interacting particles into multiple rotating crystal fragments.
Image Credit: Wayne State University/Zhi-Feng Huang

It sounds bizarre, but they exist: crystals made of rotating objects. Physicists from Aachen, Düsseldorf, Mainz and Wayne State (Detroit, USA) have jointly studied these exotic objects and their properties. They easily break into individual fragments, have odd grain boundaries and evidence defects that can be controlled in a targeted fashion. In an article published in the Proceedings of the National Academy of Sciences, the researchers outline how several new properties of such “transverse interaction” systems can be predicted by applying a comprehensive theory.

“Transverse forces” can occur in synthetic systems, such as in certain magnetic solids. They exist in systems of living organisms too, however. In an experiment observing a host of starfish embryos conducted at American university MIT, it was found that, through their swimming movements, the embryos influence each other in a manner leading them to rotate around one another. What biological function this may have is not yet understood. The common thread in these systems is that they involve rotating objects.

The key to why the universe exists may lie in an 1800s knot idea science once dismissed

The model suggests a brief “knot-dominated era,” when these tangled energy fields outweighed everything else, a scenario that could be probed through gravitational-wave signals.
Image Credit: Courtesy of Muneto Nitta/Hiroshima University

In 1867, Lord Kelvin imagined atoms as knots in the aether. The idea was soon disproven. Atoms turned out to be something else entirely. But his discarded vision may yet hold the key to why the universe exists.

Now, for the first time, Japanese physicists have shown that knots can arise in a realistic particle physics framework, one that also tackles deep puzzles such as neutrino masses, dark matter, and the strong CP problem. Their findings, in Physical Review Letters, suggest these “cosmic knots” could have formed and briefly dominated in the turbulent newborn universe, collapsing in ways that favored matter over antimatter and leaving behind a unique hum in spacetime that future detectors could listen for—a rarity for a physics mystery that’s notoriously hard to probe.

“This study addresses one of the most fundamental mysteries in physics: why our Universe is made of matter and not antimatter,” said study corresponding author Muneto Nitta, professor (special appointment) at Hiroshima University’s International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2) in Japan.

“This question is important because it touches directly on why stars, galaxies, and we ourselves exist at all.”

The Quantum Door Mystery: Electrons That Can’t Find the Exit

Photo Credit: © Technische Universität Wien

What happens when electrons leave a solid material? This seemingly simple phenomenon has eluded accurate theoretical description until now. Researchers have found the missing piece of the puzzle.

Imagine a frog sitting inside a box. The box has a large opening at a certain height. Can the frog escape? That depends on how much energy it has: if it can jump high enough, it could in principle make it out. But whether it actually succeeds is another question. The height of the jump alone isn’t enough — the frog also needs to jump through the opening.

A similar situation arises with electrons inside a solid. When given a bit of extra energy — for example, by bombarding the material with additional electrons — they may be able to escape from the material. This effect has been known for many years and is widely used in technology. But surprisingly, it has never been possible to calculate this process accurately. A collaboration between several research groups at TU Wien has now solved this mystery: just like the frog, it’s not only the energy that matters — the electron also needs to find the right “exit,” a so-called “doorway state.”

Physicists probe quark‑gluon plasma temperatures, helping paint more detailed picture of big bang

Frank Geurts is a professor of physics and astronomy at Rice and co-spokesperson of the RHIC STAR collaboration.
Photo Credit: Jeff Fitlow/Rice University.

A research team led by Rice University physicist Frank Geurts has successfully measured the temperature of quark-gluon plasma (QGP) at various stages of its evolution, providing critical insights into a state of matter believed to have existed just microseconds after the big bang, a scientific theory describing the origin and evolution of the universe. 

The study addresses the long-standing challenge of measuring the temperature of matter under extreme conditions where direct access is impossible. By using thermal electron-positron pairs emitted during ultrarelativistic heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in New York, the researchers have decoded the thermal profile of QGP. 

Temperature measurements existed previously but have been plagued by several complications such as whether they were of the QGP phase or biased by a Doppler-like effect from the large velocity fields pushing such effective temperatures.

“Our measurements unlock QGP’s thermal fingerprint,” said Geurts, a professor of physics and astronomy and co-spokesperson of the RHIC STAR collaboration. “Tracking dilepton emissions has allowed us to determine how hot the plasma was and when it started to cool, providing a direct view of conditions just microseconds after the universe’s inception.” 

Metamaterials can stifle vibrations with intentional complexity

This 3-D printed “kagome tube” can passively isolate vibrations using its complex, but deliberate, structure.
Image Credit: James McInerney, Air Force Research Laboratory

In science and engineering, it’s unusual for innovation to come in one fell swoop. It’s more often a painstaking plod through which the extraordinary gradually becomes ordinary.

But we may be at an inflection point along that path when it comes to engineered structures whose mechanical properties are unlike anything seen before in nature, also known as mechanical metamaterials. A team led by researchers at the University of Michigan and the Air Force Research Laboratory, or AFRL, have shown how to 3D print intricate tubes that can use their complex structure to stymy vibrations.

Such structures could be useful in a variety of applications where people want to dampen vibrations, including transportation, civil engineering and more. The team’s new study, published in the journal Physical Review Applied, builds on decades of theoretical and computational research to create structures that passively impede vibrations trying to move from one end to the other.

Russian Physicists Found a Way to Speed Up the Process of Developing Solar Panels

According to Ivan Zhidkov, this method allows for the quick selection of only promising materials.
 Photo Credit: Rodion Narudinov

Physicists at Ural Federal University and their colleagues from the Institute of Problems of Chemical Physics of the Russian Academy of Science (IPCP RAS) have found a way to significantly reduce the thousands of hours required for developing perovskite solar panel technology. Scientists have proposed a method that allows us  to determine in a few hours whether solar panels will fail quickly or if the development is promising with a potentially long service life. The test results were published in the journal Physica B: Condensed Matter.

Perovskite films are promising energy converters for various photoelectronic devices, such as solar cells, LEDs, and photodetectors. They have excellent optoelectronic properties and can be grown relatively easily at a low production cost.

Extra Silver Atom Sparks Breakthrough in Photoluminescence of Silver Nanoclusters

Structural architectures of anion-templated (a) Ag78 and (b) Ag79 NCs. Hydrogen atoms are omitted for clarity.
Image Credit: ©Yuichi Negishi et al.

A team of researchers from Tohoku University, Tokyo University of Science, and the Institute for Molecular Science have uncovered how the precise addition of a single silver (Ag) atom can dramatically transform the light-emitting properties of high-nuclear Ag nanoclusters (NCs). The study reports a remarkable 77-fold increase in photoluminescence (PL) quantum yield (QY) at room temperature - a milestone that paves the way for practical applications in optoelectronics and sensing technologies. The findings were published in the Journal of the American Chemical Society.

Photoluminescence quantum yield is an important metric used to evaluate the efficiency of photoluminescence, which is how well a material can absorb energy and convert it into light. Improving PLQY positively impacts technology such as OLEDs in TV screens.

Finding treasures with physics: the fingerprint matrix

Left: Artistic impression of metal spheres buried in small glass beads. Middle: Conventional ultrasound picture. Right: With the new technology, the positions of the metal spheres can be precisely determined.
Image Credit: © TU Wien / Arthur Le Ber

How do you find objects buried in sand or hidden in thick fog? A team from the Institut Langevin (Paris) and TU Wien (Vienna) has developed an astonishing method.

Can we reveal objects that are hidden in environments completely opaque to the human eye? With conventional imaging techniques, the answer is no: a dense cloud or layer of material blocks light so completely that a simple photograph contains no information about what lies behind it.

However, a research collaboration between the Institut Langevin and TU Wien has now shown that, with the help of innovative mathematical tricks, objects can be detected even in such cases – using what is known as the ‘fingerprint matrix’. The team tested the newly developed method on metal objects buried in sand and in applications in the field of medical imaging. A joint publication on this topic has just appeared in the journal Nature Physics.

Scientists uncover room-temperature route to improved light-harvesting and emission devices

Dasom Kim
Photo Credit: Jorge Vidal/Rice University

Atoms in crystalline solids sometimes vibrate in unison, giving rise to emergent phenomena known as phonons. Because these collective vibrations set the pace for how heat and energy move through materials, they play a central role in devices that capture or emit light, like solar cells and LEDs.

A team of researchers from Rice University and collaborators have found a way to make two different phonons in thin films of lead halide perovskite interact with light so strongly that they merge into entirely new hybrid states of matter. The finding, reported in a study published in Nature Communications, could provide a powerful new lever for controlling how perovskite materials harvest and transport energy.

To get a specific light frequency in the terahertz range to interact with phonons in the halide perovskite crystals, the researchers fabricated nanoscale slots ⎯ each about a thousand times thinner than a sheet of cling wrap ⎯ into a thin layer of gold. The slots acted like tiny metallic traps for light, tuning its frequency to that of the phonons and thus giving rise to a strong form of interaction known as “ultrastrong coupling.”

Scientists solve mystery of loop current switching in Kagome metals

Structure and electron behavior in kagome metals: (A) The triangular atomic arrangement showing how tiny electrical currents flow in loops. (B) How electrons organize into wave-like density patterns. (C) How electrons normally move through the material. (D) How electron movement is affected by the wave patterns. (E) The special combined state where both loop currents and wave patterns exist together, creating the conditions for magnetic switching.
Image Credit: Tazai et al., 2025

Quantum metals are metals where quantum effects—behaviors that normally only matter at atomic scales—become powerful enough to control the metal's macroscopic electrical properties. 

Researchers in Japan have explained how electricity behaves in a special group of quantum metals called kagome metals. The study is the first to show how weak magnetic fields reverse tiny loop electrical currents inside these metals. These switching changes the material's macroscopic electrical properties and reverses which direction has easier electrical flow, a property known as the diode effect, where current flows more easily in one direction than the other.  

More Signs of Phase-change 'Turbulence' in Nuclear Matter

 A view from the ground up of the three-story STAR detector at the Relativistic Heavy Ion Collider (RHIC).
Image Credit: Brookhaven National Laboratory

Members of the STAR Collaboration, a group of physicists collecting and analyzing data from particle collisions at the Relativistic Heavy Ion Collider (RHIC), have published a new high-precision analysis of data on the number of protons produced in gold-ion smashups over a range of energies. The results, published in Physical Review Letters, suggest one part of a key signature of a so-called “critical point.” That’s a unique point on the “map” of nuclear phases that marks a change in the way quarks and gluons, the building blocks of protons and neutrons, transform from one phase of matter to another.

Discovering the critical point has been a central goal of research at RHIC, a U.S. Department of Energy (DOE) Office of Science user facility for nuclear physics research at DOE’s Brookhaven National Laboratory. Like centuries-old efforts to map out the solid, liquid, and gaseous phases of substances like water, it’s considered essential for fully understanding and describing the quark-gluon plasma. This unique form of nuclear matter is generated by RHIC’s most energetic nuclear collisions, which effectively “melt” the protons and neutrons that make up the colliding gold ions, briefly liberating their innermost building blocks to form a nearly perfect fluid state that once filled our early universe.

New type of time crystals discovered

Time crystal 
Correlations between quantum particles result in a rhythmic signal – without the need for an external beat to set the tempo.
Image Credit: © TU Wien

Nature has many rhythms: the seasons result from the Earth's movement around the sun; the ticking of a pendulum clock results from the oscillation of its pendulum. These phenomena can be understood with very simple equations.

However, regular rhythms can also arise in a completely different way – by themselves, without an external clock, through the complex interaction of many particles. Instead of uniform disorder, a fixed rhythm emerges – this is referred to as a ‘time crystal’. Calculations by TU Wien (Vienna) now show that such time crystals can also be generated in a completely different way than previously thought. The quantum physical correlations between the particles, which were previously thought to be harmful for the emergence of such phenomena, can actually stabilize time crystals. This is a surprising new insight into the quantum physics of many-particle systems.

Mixing neutrinos of colliding neutron stars changes how merger unfolds

New simulations of neutron star mergers reveal that the mixing and changing of tiny particles called neutrinos impacts how the merger unfolds, including the composition and structure of the merger remnant as well as the resulting emissions. This image depicts the density of neutrinos within the remnant as varying textures, and the colors represent energy densities of different neutrino flavors.
 Image Credit: Provided by the Radice research group / Pennsylvania State University
(CC BY-NC-ND 4.0)

The collision and merger of two neutron stars — the incredibly dense remnants of collapsed stars — are some of the most energetic events in the universe, producing a variety of signals that can be observed on Earth. New simulations of neutron star mergers by a team from Penn State and the University of Tennessee Knoxville reveal that the mixing and changing of tiny particles called neutrinos that can travel astronomical distances undisturbed impacts how the merger unfolds, as well as the resulting emissions. The findings have implications for longstanding questions about the origins of metals and rare earth elements as well as understanding physics in extreme environments, the researchers said.

The paper, published in the journal Physical Review Letters, is the first to simulate the transformation of neutrino “flavors” in neutron star mergers. Neutrinos are fundamental particles that interact weakly with other matter, and come in three flavors, named for the other particles they associate with: electron, muon and tau. Under specific conditions, including the inside of a neutron star, neutrinos can theoretically change flavors, which can change the types of particles with which they interact.

Measuring the quantum W state

Achieving the entanglement measurement of the W state
Image Credit: KyotoU / Takeuchi lab

The concept of quantum entanglement is emblematic of the gap between classical and quantum physics. Referring to a situation in which it is impossible to describe the physics of each photon separately, this key characteristic of quantum mechanics defies the classical expectation that each particle should have a reality of its own, which gravely concerned Einstein. Understanding the potential of this concept is essential for the realization of powerful new quantum technologies.

Developing such technologies will require the ability to freely generate a multi-photon quantum entangled state, and then to efficiently identify what kind of entangled state is present. However, when performing conventional quantum tomography, a method commonly used for state estimation, the number of measurements required grows exponentially with the number of photons, posing a significant data collection problem.

Innovative target design leads to surprising discovery in laser-plasma acceleration

Researchers studying laser-driven proton acceleration introduced an innovative, self-replenishing water sheet target to address the inefficiency of replacing targets after each laser pulse. The target had a surprising side effect, resulting in a naturally focused, more tightly aligned proton beam. 
Image Credit: Greg Stewart/SLAC National Accelerator Laboratory)

Scientists have developed a groundbreaking method for generating fast, bright proton beams using a high-repetition-rate laser-plasma accelerator. This work, published in Nature Communications, resolves several long-standing challenges and ushers this technology to the threshold of real-world applications – all thanks to a stream of water. 

“These exciting results pave the way for new applications of relativistic high-power lasers for applications in medicine, accelerator research, and inertial fusion,” said Siegfried Glenzer, professor of photon science and the director of the High Energy Density Science division at the Department of Energy's SLAC National Accelerator Laboratory. 

Women of Science: A Legacy of Achievement

Future generations to pursue their passions and break down barriers in the pursuit of knowledge.
Image Credit: Scientific Frontline stock image

Throughout history, women have made groundbreaking contributions to science, despite facing significant societal barriers and a lack of recognition. Their relentless pursuit of knowledge and innovation has shaped our understanding of the world and paved the way for future generations of scientists. This article celebrates the achievements of some of these remarkable women, highlighting their struggles and the impact of their work.

The women featured in this article, along with countless others throughout history, have made invaluable contributions to the advancement of science. Their achievements, often accomplished in the face of adversity and societal barriers, have shaped our understanding of the world and paved the way for future generations of scientists. These women demonstrate the power of perseverance, the importance of challenging established norms, and the profound impact that individual dedication can have on scientific progress. By recognizing and celebrating their legacies, we not only honor their contributions but also inspire future generations to pursue their passions and break down barriers in the pursuit of knowledge.

First distributed quantum algorithm brings quantum supercomputers closer

Dougal Main and Beth Nichol working on the distributed quantum computer.
Photo Credit: John Cairns.

In a milestone that brings quantum computing tangibly closer to large-scale practical use, scientists at Oxford University’s Department of Physics have demonstrated the first instance of distributed quantum computing. Using a photonic network interface, they successfully linked two separate quantum processors to form a single, fully connected quantum computer, paving the way to tackling computational challenges previously out of reach. The results have been published in Nature. 

The breakthrough addresses quantum’s ‘scalability problem’: a quantum computer powerful enough to be industry-disrupting would have to be capable of processing millions of qubits. Packing all these processors in a single device, however, would require a machine of an immense size. In this new approach, small quantum devices are linked together, enabling computations to be distributed across the network. In theory, there is no limit to the number of processors that could be in the network.  

Novel processor uses magnons to crack complex problems

The three first authors of the paper - Noura Zenbaa (on the right), Claas Abert (on the left) and Fabian Majcen (in the middle) at the moment when the universal inverse-design magnonic device was activated to solve its first problem.
Photo Credit: Andrii Chumak, NanoMag, U of Vienna

An international team of researchers, led by physicists from the University of Vienna, has achieved a breakthrough in data processing by employing an "inverse-design" approach. This method allows algorithms to configure a system based on desired functions, bypassing manual design and complex simulations. The result is a smart "universal" device that uses spin waves ("magnons") to perform multiple data processing tasks with exceptional energy efficiency. Published in Nature Electronics, this innovation marks a transformative advance in unconventional computing, with significant potential for next-generation telecommunications, computing, and neuromorphic systems.

Modern electronics face critical challenges, including high energy consumption and increasing design complexity. In this context, magnonics — the use of magnons, or quantized spin waves in magnetic materials — offers a promising alternative. Magnons enable efficient data transport and processing with minimal energy loss. With the growing demand for innovative computing solutions, ranging from 5G and upcoming 6G networks to neuromorphic computing (mimicking functions of the brain), magnonics represents a paradigm shift that redefines how devices are designed and operated. Developing an innovative magnonic processor that enables highly adaptive and energy-efficient computing was a challenge that Andrii Chumak of the University of Vienna's Nanomagnetism and Magnonics Group and his collaborators successfully met.

The metal that does not expand

Metal usually expands when heated
Photo Credit: Courtesy of Technische Universität Wien

Breakthrough in materials research: an alloy of several metals has been developed that shows practically no thermal expansion over an extremely large temperature interval.

Most metals expand when their temperature rises. The Eiffel Tower, for example, is around 10 to 15 centimeters taller in summer than in winter due to its thermal expansion. However, this effect is extremely undesirable for many technical applications. For this reason, the search has long been on for materials that always have the same length regardless of the temperature. Invar, for example, an alloy of iron and nickel, is known for its extremely low thermal expansion. How this property can be explained physically, however, was not entirely clear until now.

Now, a collaboration between theoretical researchers at TU Wien (Vienna) and experimentalists at University of Science and Technology Beijing has led to a decisive breakthrough: using complex computer simulations, it has been possible to understand the invar effect in detail and thus develop a so-called pyrochlore magnet – an alloy that has even better thermal expansion properties than invar. Over an extremely wide temperature range of over 400 Kelvins, its length only changes by around one ten-thousandth of one per cent per Kelvin.