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Category: particle physics

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.

Tiny particles ‘surf’ microcosmic waves to save energy in chaotic environments

Conditions can get rough in the micro- and nanoworld. For example, to ensure that nutrients can still be optimally transported within cells, the minuscule transporters involved need to respond to the fluctuating environment. Physicists at Heinrich Heine University Düsseldorf (HHU) and Tel Aviv University in Israel have used model calculations to examine how this can succeed. They have now published their results—which could also be relevant for future microscopic machines—in the journal Nature Communications.

Scientists Discover How To “Purify” Light, Paving the Way for Faster, More Secure Quantum Technology

University of Iowa scientists have identified a new way to “purify” photons, a development that could improve both the efficiency and security of optical quantum technologies.

The team focused on two persistent problems that stand in the way of producing a reliable stream of single photons, which are essential for photonic quantum computers and secure communication systems. The first issue, known as laser scatter, arises when a laser is aimed at an atom to trigger the release of a photon, the basic unit of light. Although this method successfully generates photons, it can also produce extra, unwanted ones. These additional photons reduce the efficiency of the optical system, similar to how stray electrical currents interfere with electronic circuits.

A second complication comes from the way atoms occasionally respond to laser light. In uncommon cases, an atom releases more than one photon at the same time. When this happens, the precision of the optical circuit suffers because the extra photons disrupt the intended orderly flow of single photons.

Neurons use physical signals, not electricity, to stabilize communication

Every movement you make and every memory you form depends on precise communication between neurons. When that communication is disrupted, the brain must rapidly rebalance its internal signaling to keep circuits functioning properly. New research from the USC Dornsife College of Letters, Arts and Sciences shows that neurons can stabilize their signaling using a fast, physical mechanism—not the electrical activity scientists long assumed was required.

The discovery, published recently in Proceedings of the National Academy of Sciences, reveals a system that doesn’t depend on the flow of charged particles to maintain signaling when part of a synapse—the junction between neurons—suddenly stops working.

Maintaining this balance between neurons is essential for muscle control, learning and overall brain health. Failure to maintain this “homeostasis” has been linked to neurological conditions such as epilepsy and autism.

CERN Scientists Solve Decades-Old Particle Physics Mystery

Researchers from TUM, working at CERN, have made a groundbreaking discovery that reveals how deuterons are formed. Another long-standing question in particle physics has been answered. Scientists working with the ALICE experiment at CERN’s Large Hadron Collider (LHC), led by researchers from the

Cracking the mystery of heat flow in few-atoms thin materials

For much of my career, I have been fascinated by the ways in which materials behave when we reduce their dimensions to the nanoscale. Over and over, I’ve learned that when we shrink a material down to just a few nanometers in thickness, the familiar textbook rules of physics begin to bend, stretch, or sometimes break entirely. Heat transport is one of the areas where this becomes especially intriguing, because heat is carried by phonons—quantized vibrations of the atomic lattice—and phonons are exquisitely sensitive to spatial confinement.

A few years ago, something puzzling emerged in the literature. Molecular dynamics simulations showed that ultrathin silicon films exhibit a distinct minimum in their thermal conductivity at around one to two nanometers thickness, which corresponds to just a few atomic layers. Even more surprisingly, the thermal conductivity starts to increase again if the material is made even thinner, approaching extreme confinement and the 2D limit.

This runs counter to what every traditional model would predict. According to classical theories such as the Boltzmann transport equation or the Fuchs–Sondheimer boundary-scattering framework, reducing thickness should monotonically suppress thermal conductivity because there is simply less room for phonons to travel freely and carry heat around. Yet the simulations done by the team of Alan McGaughey at Carnegie Mellon University in Pittsburgh insisted otherwise, and no established theory could explain why.

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