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Category: particle physics

Shortest light pulse ever created captures ultrafast electron dynamics

Electrons determine everything: how chemical reactions unfold, how materials conduct electricity, how biological molecules transfer energy, and how quantum technologies operate. But electron dynamics happens on attosecond timescales—far too fast for conventional measurement tools.

Researchers have now generated a 19.2-attosecond soft X-ray pulse, which effectively creates a camera capable of capturing these elusive dynamics in real time with unprecedented detail, enabling the observation of processes never observed before. Dr. Fernando Ardana-Lamas, Dr. Seth L. Cousin, Juliette Lignieres, and ICREA Prof. Jens Biegert, at ICFO, has published this new record in Ultrafast Science. At just 19.2 attoseconds long, it is the shortest and brightest soft X-ray pulse ever produced, giving rise to the fastest “camera” in existence.

Flashes of light in the soft X-ray spectral range provide fingerprinting identification, allowing scientists to track how electrons reorganize around specific atoms during reactions or phase transitions. Generating an isolated pulse this short, required innovations in high-harmonic generation, advanced laser engineering, and attosecond metrology. Together, these developments allow researchers to observe electron dynamics, which define material properties, at their natural timescales.

Color-superconducting quark matter may explain stability of massive neutron stars

Describing matter under extreme conditions, such as those found inside neutron stars, remains an unsolved problem. The density of such matter is equivalent to compressing around 100,000 Eiffel Towers into a single cubic centimeter. In particular, the properties of so-called quark matter—which consists of the universe’s fundamental building blocks, the quarks, and may exist in extremely dense regions—play a central role.

Researchers from TU Darmstadt and Goethe University Frankfurt have studied this matter and its thermodynamic properties. Their findings are published in the journal Physical Review Letters.

Theoretical studies suggest that quarks at very low temperatures enter a so-called color-superconducting state, which fundamentally alters the nature of matter. This state is analogous to the transition of an electron gas into an electrical superconductor—except that, instead of electrons, quarks pair up and create an energy gap in their excitation spectrum.

Electrochemical tuning of Ni-rich cathodes curbs c-collapse, enhancing lithium-ion battery durability

Lithium-ion batteries (LiBs) remain the most widely used rechargeable batteries worldwide, due to their light weight, high energy densities and their short charging times. Energy engineers have been trying to identify new materials and strategies that could help to further boost the energy stored by LiBs, while also extending their lifespan (i.e., the period for which they can be used reliably).

LiBs work by moving charged lithium atoms (i.e., ions) between a positive electrode (i.e., cathode) and a negative electrode (i.e., anode). When lithium ions enter and leave these materials, they can experience significant structural changes.

These changes include the sudden shrinkage of the spacing between the materials’ horizontal layers, which can be experimentally monitored through the crystal’s c-lattice parameter. This phenomenon, referred to as c-collapse, can deform the material, crack the particles and in turn shorten the life of batteries.

New Microscope Makes an Invisible 2D Material Visible

A new microscopy technique allows scientists to see single-atom-thick boron nitride by making it glow under infrared light. Researchers from the Physical Chemistry and Theory departments at the Fritz Haber Institute have developed a new way to visualize boron nitride layers that are just one atom

Celebrating two decades of global scientific computing

Imagine a planetary computer capable of storing and processing hundreds of petabytes of data for the research needs of a worldwide community of scientists. This is the Worldwide LHC Computing Grid (WLCG), which is celebrating its 20th anniversary.

Originally conceived to handle the unprecedented data volumes of the Large Hadron Collider (LHC), the WLCG has evolved into a global network connecting hundreds of computing centres across more than 40 countries. It enables thousands of scientists worldwide to store, process and analyse massive amounts of data in quasi-real time, supporting discoveries in particle physics.

On 8 December, a special event at the CERN Science Gateway brought together the international community that has turned this ambitious project into one of the largest distributed computing collaborations in the world. Key figures from the project highlighted its history, challenges and future prospects. Les Robertson, whose efforts and leadership were instrumental during the early days of the Grid, reflected on how the idea was born and the challenges of building something that had never been done before. It was an ambitious idea for its time, one that required both technological innovation and unprecedented cooperation across countries. Yet this early confidence proved justified: the Grid rapidly moved from concept to reality, paving the way for a new model of large-scale scientific computing.

The Universal Law Behind Market Price Swings

Analysis of a large dataset from the Tokyo Stock Exchange validates a universal power law relating the price of a traded stock to the traded volume.

One often hears that economics is fundamentally different from physics because human behavior is unpredictable and the economic world is constantly changing, making genuine “laws” impossible to establish. In this view, markets are never in a stable state where immutable laws could take hold. I beg to differ. The motion of particles is also unpredictable, and many physical systems operate far from equilibrium. Yet, as Phil Anderson argued in a seminal paper [1], universal laws can still emerge at the macroscale from the aggregation of widely diverse microscopic behaviors. Examples include not only crowds in stadiums or cars on highways but also economic agents in markets.

Now Yuki Sato and Kiyoshi Kanazawa of Kyoto University in Japan have provided compelling evidence that one such universal law governs financial markets. Using an unprecedentedly detailed dataset from the Tokyo Stock Exchange, they found that a single mathematical law describes how the price of every traded stock responds to trading volume [2] (Fig. 1). The result is a striking validation of physics-inspired approaches to social sciences, and it might have far-reaching implications for how we understand market dynamics.

Converting Spin Waves to Vibrational Waves

The demonstration of wave conversion may lead to spintronic technology that transmits fragile spin data as acoustic waves.

A branch of electronic device engineering called spintronics uses electron spins to store and transmit information. A research team has now opened up new possibilities for information processing with spins by showing how spin signals can be translated into acoustic signals (phonons) that can be transmitted through materials [1]. Phonons can travel undisturbed for longer distances, so this conversion might extend the capabilities of spintronics, much as the conversion of electrical pulses into light is used for long-distance telecommunication.

In a spin current, electrons that are preferentially aligned in one spin state can be thought of as remaining stationary while a wave of spin reorientation passes through the material. Spin currents are already used in devices such as specialized magnetic memories and other computing elements, in which information is encoded and transferred using the spins.

Newly engineered giant superatoms show promise for reliable quantum state transfer

Quantum technologies are systems that leverage quantum mechanical effects to perform computations, share information or perform other functions. These systems rely on quantum states, which need to be reliably transferred and protected against decoherence (i.e., a gradual loss of quantum information).

In recent years, quantum physicists and engineers have introduced so-called giant atoms, artificial structures that behave like enlarged atoms and could be used to develop quantum technologies. In a recent paper published in Physical Review Letters, researchers at Chalmers University of Technology built on this concept and introduced new carefully engineered giant ‘superatoms’ (GSAs), a new type of giant-atom-like structures that could generate entanglement and enable the reliable transfer of quantum states between different such devices.

“Over the past years, there has been growing interest in so-called ‘giant atoms,’ which are quantum emitters that couple to their environment at multiple, spatially separated points,” Lei Du, first author of the paper, told Phys.org.

Scientists create stable, switchable vortex knots inside liquid crystals

The knots in your shoelaces are familiar, but can you imagine knots made from light, water, or from the structured fluids that make LCD screens shine?

They exist, and in a new Nature Physics study, researchers created particle-like so-called “vortex knots” inside chiral nematic liquid crystals, a twisted fluid similar to those used in LCD screens. For the first time, these knots are stable and could be reversibly switched between different knotted forms, using electric pulses to fuse and split them.

“These particle-like topological objects in liquid crystals share the same kind of topology found in theoretical models of glueballs, experimentally-elusive theoretical subatomic particles in high-energy physics, in hopfions and heliknotons studied in light, magnetic materials, and in vortex knots found across many other systems,” explains Ivan Smalyukh, director of the Hiroshima University WPI-SKCM² Satellite at the University of Colorado Boulder and a professor in CU Boulder’s Department of Physics.

Dark matter search narrows as detector sets new limits and spots solar neutrinos

Australian researchers have played a central role in a landmark result from the LUX-ZEPLIN (LZ) experiment in South Dakota—the world’s most sensitive dark matter detector. Today, scientists working on the experiment report they have further narrowed constraints on proposed dark matter particles. And, for the first time, the experiment has detected elusive neutrinos produced deep inside the sun.

Scientists hypothesize that dark matter makes up about a quarter of the universe’s mass (or 85% of its matter) but have yet to detect exactly what makes up this strange phenomenon. The result announced today by the LZ experiment is one of the world’s most sensitive measurements in the hunt for dark matter. It has expanded its search for WIMPs (weakly interacting massive particles) down to masses approximately between that of three and nine times that of a proton, the positively charged particle in the nucleus of an atom.

Dr. Theresa Fruth, from the University of Sydney’s School of Physics, is one of only two Australian-based researchers in the 250-member international collaboration.

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