Toggle light / dark theme

Get the latest international news and world events from around the world.

Log in for authorized contributors

Sudden quantum jolts may not break adiabatic behavior after all

In thermodynamics, an “adiabatic process” is a system change that transfers no heat in or out of the system. Any and all energy change in that system are therefore accomplished by doing work on the system, work being action that moves matter over a distance. (An example is a bicycle tire pump or lifting a box from the floor.)

The “adiabatic theorem” says that if you change a system slowly enough, it will remain in the same energy state. For example, if you walk slowly enough holding a full cup of coffee, the coffee will not spill—the coffee system has time to relax back to its steady state—but if you make a quick and sudden change while holding the coffee cup, some coffee will spill over the cup’s edge.

There is a similar theorem in quantum mechanics—a quantum system that is changed (perturbed) slowly enough will remain in its existing quantum state (often its ground state), while a sudden change, such as a photon impinging upon an atom, changes its energy state.

Twisting water reveals hidden order across four molecular layers at air-water interface

Researchers from the Department of Physical Chemistry at the Fritz Haber Institute and Freie Universität Berlin have revealed the arrangement of water molecules at the interface between liquid water and air. Their findings help to better understand interfacial chemistry, which is largely determined by the specific arrangement of the water molecules. Published in Science Advances, the study shows that one parameter in particular—one that has been neglected until now—is of fundamental importance: the water twist.

Water is arguably the most important molecule on Earth. Interfaces of water play a critical role in numerous processes within physiology, at the ocean surface, and in the atmosphere. In these processes, it is primarily the incredibly thin region of water directly at the boundary that governs their behavior.

Crucially, the sheer presence of the interface perturbs the molecular structure of water, generating preferential orientations and an altered hydrogen-bond network, which give rise to profoundly different properties of water in that region. While these unique structures are at the heart of many interfacial phenomena, characterizing them is monumentally difficult.

A new way to understand the evolution of spacetime dynamics

The concept of spacetime, first described in Einstein’s theory of general relativity, has since been widely studied by many physicists worldwide. Spacetime is described mathematically as a four-dimensional (4D) continuum in which physical events occur, which merges three-dimensional (3D) space, with one-dimensional (1D) time.

This 4D continuum is known to continuously evolve following complex and intricate patterns that are governed by Einstein’s field equations; mathematical equations that describe how matter and energy shape spacetime. While various past theoretical studies explored the evolution of spacetime, identifying patterns that persist during its evolution has proved challenging so far.

Researchers at Adolfo Ibáñez University in Chile and Columbia University set out to explore the evolution of spacetime using ideas rooted in nonlinear electrodynamics, an area of physics that studies the behavior of electric and magnetic fields in complex materials.

Your hand betrays your sense of fairness, and it does so before you even realize it

It turns out that your body is much more truthful about what is and isn’t fair than you might imagine. The rate at which we make physical movements is able to reveal whether our motives are self-interested or retaliatory.

Imagine you’re offered a split of money in an Ultimatum Game: accept a generous share or reject an insultingly low one. Your facial expression might show disgust—but what about your hand?

In new research published in The Royal Society Open Science, scientists report that the speed and vigor of our gestures reveal what we truly care about. In typical choices, people move faster toward bigger rewards; movement vigor usually tracks subjective value. But life’s deals aren’t all about personal gain—notions of fairness and punishment often enter play. Can the way we physically reach for a choice uncover these hidden social motives?

Measurement of nuclear reactions at record-low energies opens new pathways for astrophysics research

An international research team has achieved an important milestone for astrophysics at GSI/FAIR in Darmstadt: In the CRYRING@ESR storage ring, scientists were able to measure nuclear reactions at extremely low energies for the first time, mirroring the conditions inside stars. This novel experimental approach lays the foundation for decoding the formation of elements in the universe with even greater precision in the future.

In the extreme environments of stars, nuclear processes often occur at very low energies. These so-called “sub-MeV energies” (below 1 megaelectron volt) are difficult to replicate in the laboratory because the probability of atomic nuclei interacting at such low speeds is exceptionally small.

In the FAIR storage ring CRYRING@ESR, researchers were able to lower the energy available for the nuclear reaction in the center-of-mass frame of the two particles down to 403 kiloelectron volts. This marks a new record: It is the lowest energy at which a nuclear reaction has ever been measured in a heavy-ion storage ring. The new findings were recently published in the journal European Physical Journal A.

Perovskite solar cells skip yellow phase, degrade more slowly with key additives

Halide perovskites are gaining ground on silicon as a critical material for solar cell technologies: A new study published in the journal Science reports a method to make perovskite-based photovoltaics more durable, allowing the films to attain the desirable black phase of crystal configuration quicker and at lower temperatures while also making it harder to degrade into the inactive yellow phase.

Perovskites are solution-processable materials and can be readily processed as a solution or deposited as vapor. By mixing two key ingredients in the precursor solution, Rice University chemical engineer Aditya Mohite and collaborators have developed perovskite crystalline films that retain 98% of their initial efficiency even after 1,200 hours of exposure under open-circuit voltage conditions to accelerate aging at 90 degrees Celsius (194 degrees Fahrenheit).

The two additives used were a two-dimensional perovskite, which served as a template to guide crystal growth, and formamidinium chloride, a salt molecule that regulates crystallization and has the optimal size to sustain the atomic bonds in the crystal in the right configuration. The two additives create compressive strain in the lattice, driving the formation of the black perovskite phase and stabilizing it, while also steering degradation toward a harder-to-form phase, significantly improving durability.

Light unlocks full polarization control at ultrafast speeds, reshaping photonics

Scientists at Heriot‑Watt University have demonstrated in a world-first, that light can be used to control every aspect of how electromagnetic waves oscillate, opening new technological frontiers. Researchers working in photonics, the science of light, have discovered a new way to control “polarization,” a key property of light that plays a crucial role in the performance of technologies such as drug development and quantum computers.

The breakthrough resolves a long-standing challenge in photonics: achieving control of light that is both fast and strong enough to be useful in real systems. The research, titled All-optical polarization control in time-varying low index films via plasma symmetry breaking, has been published in the journal Nature Photonics.

Dr. Marcello Ferrera, Professor at Heriot-Watt University’s School of Engineering and Physical Sciences, said, How light oscillates has a huge impact on how it interacts with the physical world around us. For the first time, we now have full control over this property of light, for any polarization state, and at ultra‑fast speeds.

Room-temperature multiferroic could pave way to low-energy computing

A team of researchers at Rice University has engineered a new version of a well-known multiferroic that exhibits orders of magnitude higher performance at room temperature than its parent material. The study, published in the Proceedings of the National Academy of Sciences, describes a modified version of bismuth ferrite that shows a 10-fold increase in magnetization and 100-fold increase in magnetoelectric coupling compared to standard varieties.

The synthesis process entailed mixing bismuth ferrite with barium titanate while simultaneously growing the material as a thin film on a substrate that distorts its crystal structure.

“Nobody had ever dialed both knobs—the strain and the chemistry—at once,” said Rice materials scientist Lane Martin, who led the study. “We were able to combine two different material systems into a new material with a new structure and a new combination of properties.”

Superconducting quantum circuit simulates proton tunneling phenomenon in chemical systems

Researchers at Yale, Google, and the University of California-Santa Barbara have created a device that simulates the quantum “tunneling” behavior of protons that occurs in chemistry, a process so common it occurs in everything from photosynthesis to the formation of human DNA.

The advance has the potential to aid researchers across a variety of disciplines, including the development of new solar fuels, pharmaceuticals, and materials. It is described in a new study in the journal PRX Quantum.

Quantum tunneling is a mechanism by which particles, such as electrons or protons, pass through an energy barrier they should not have sufficient energy to cross.

Gene circuits reshape DNA folding and affect how genes are expressed, study finds

When a gene is turned on in a cell, it creates a ripple effect along the DNA strand, changing the physical structure of the strand. A new study by MIT researchers, appearing in Science, shows that these ripples can stimulate or suppress neighboring genes. These effects, which result from the winding or unwinding of neighboring DNA, are determined by the order of genes along a strand of DNA. Genes upstream of the active gene are usually turned up, while those downstream are inhibited.

The new findings offer guidance that could make it easier to control the output of synthetic gene circuits. By altering the relative ordering and arrangement of genes (gene syntax), researchers could create circuits that synergize to maximize their output, or that alternate the output of two different genes.

“This is really exciting because we can coordinate gene expression in ways that just weren’t possible before,” says Katie Galloway, an assistant professor of chemical engineering at MIT. “Syntax will be really useful for dynamic circuits. Now we have the ability to select not only the biochemistry of circuits, but also the physical design to support dynamics.”

/* */