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Trilayer moiré superlattices unlock tunable control of exciton configurations

Moiré superlattices are periodic patterns formed when two or more thin semiconducting layers are stacked with a small twist angle or lattice mismatch. When 2D materials form these patterns, their electronic, mechanical, and optical properties can change significantly.

Over the past decades, moiré superlattices have emerged as a promising platform to study unconventional and unknown physical states. They also enabled the observation of unique excitonic configurations (i.e., arrangements of bound electron-hole pairs).

In bilayer moiré systems based on two-dimensional transition metal dichalcogenides (TMDCs), for instance, physicists have observed interlayer dipolar excitons. These are excitons produced when an electron and a hole are bound together across different layers in a stacked 2D semiconductor.

New quantum sensors can withstand extreme pressure

The world of quantum physics is already mysterious, but what happens when that strange realm of subatomic particles is put under immense pressure? Observing quantum effects under pressure has proven difficult for a simple reason: Designing sensors that can withstand extreme forces is challenging.

In a significant advance, a team led by physicists at WashU has created in an unbreakable sheet of crystallized . The sensors can measure stress and magnetism in materials under pressure that exceeds 30,000 times the pressure of the atmosphere.

“We’re the first ones to develop this sort of high-pressure sensor,” said Chong Zu, an assistant professor of physics in Arts & Sciences and a member of Washington University in St. Louis’ Center for Quantum Leaps. “It could have a wide range of applications in fields ranging from quantum technology, , to astronomy and geology.”

Soft magnetoelastic sensor measures fatigue from eyeball movements in real-time

Over the past few decades, electronics engineers have developed increasingly sophisticated sensors that can reliably measure a wide range of physiological signals, including heart rate, blood pressure, respiration rate and oxygen saturation. These sensors were used to create both biomedical and consumer-facing wearable devices, advancing research and the real-time monitoring of health-related metrics, such as sleep quality and physiological stress.

Fatigue, a mental state marked by a decline in performance due to stress, lack of sleep, excessive activity or other factors, has proved to be more difficult to reliably quantify. Most existing methods for measuring fatigue rely on surveys that ask people to report how tired they feel, a method to record the brain’s electrical activity known as electroencephalography (EEG) or camera-based systems.

Most of these approaches are unreliable or only applicable in laboratory settings, as they rely on subjective evaluations, bulky equipment or controlled environments. These limitations prevent their large-scale deployment in everyday settings.

Ultra-flat optic pushes beyond what was previously thought possible

Cameras are everywhere. For over two centuries, these devices have grown increasingly popular and proven to be so useful, they have become an indispensable part of modern life.

Today, they are included in a vast range of applications—everything from smartphones and laptops to security and to cars, aircraft, and satellites imaging Earth from high above. And as an overarching trend toward miniaturizing mechanical, optical, and electronic products continues, scientists and engineers are looking for ways to create smaller, lighter, and more energy-efficient cameras for these technologies.

Ultra-flat optics have been proposed as a solution for this engineering challenge, as they are an alternative to the relatively bulky lenses found in cameras today. Instead of using a curved lens made out of glass or plastic, many ultra-flat optics, such as metalenses, use a thin, flat plane of microscopic nanostructures to manipulate light, which makes them hundreds or even thousands of times smaller and lighter than conventional camera lenses.

Synthetic magnetic fields steer light on a chip for faster communications

Electrons in a magnetic field can display striking behaviors, from the formation of discrete energy levels to the quantum Hall effect. These discoveries have shaped our understanding of quantum materials and topological phases of matter. Light, however, is made of neutral particles and does not naturally respond to magnetic fields in the same way. This has limited the ability of researchers to reproduce such effects in optical systems, particularly at the high frequencies used in modern communications.

To address this challenge, researchers from Shanghai Jiao Tong University and Sun Yat-Sen University have developed a method for generating pseudomagnetic fields—synthetic fields that mimic the influence of real magnetic fields—inside nanostructured materials known as photonic crystals.

Unlike previous demonstrations, which focused on specific effects such as photonic Landau levels, the new approach allows arbitrary control of how light flows within the material. Their research is published in Advanced Photonics.

Nanoscale images of protein complex reveal secret to blood clotting chain reaction

If you’ve ever accidentally sliced yourself on broken glass or a piece of paper, you may have noticed that the bleeding can be hard to stop. Scientists have long wondered how the cascade of events that leads to blood clotting is triggered, especially since the process has life and death consequences. Too little clotting and you bleed out, while too much can cause a heart attack or stroke.

Microscopes can now watch materials go quantum with liquid helium

A new specimen holder gives scientists more control over ultra-cold temperatures, enabling the study of how materials acquire properties useful in quantum computers.

Scientists can now reliably chill specimens near absolute zero for over 10 hours while taking images resolved to the level of individual atoms with an . The new capability comes from a liquid-helium-cooled sample holder designed by a team of scientists and engineers at the University of Michigan and Harvard University.

Conventional instruments can usually maintain such an extreme temperature, about-423 degrees Fahrenheit or 20 degrees above absolute zero, for a few minutes, capping out at a few hours. But longer periods of time are needed to take atomic-resolution images of candidate materials for advanced technologies.

Laser reveals sound from supersonic molecules in near-space cold conditions

What happens when you hurl molecules faster than sound through a vacuum chamber nearly as cold as space itself? At the University of Missouri, researchers are finding out—and discovering new ways to detect molecules under extreme conditions.

The discovery could one day help chemists unravel the mysteries of astrochemistry, offering new clues about what the universe is made of, how stars and planets form and even where life originated.

In a recent study published in The Journal of Physical Chemistry A, Mizzou faculty member Arthur Suits and doctoral student Yanan Liu fired a laser at methane gas molecules moving faster than the in a at roughly −430°F, close to the temperature in parts of outer space.

Atom-thin crystals provide new way to power the future of computer memory

Picture the smartphone in your pocket, the data centers powering artificial intelligence, or the wearable health monitors that track your heartbeat. All of them rely on energy-hungry memory chips to store and process information. As demand for computing resources continues to soar, so does the need for memory devices that are smaller, faster, and far more efficient.

A new study by Auburn physicists has taken an important step toward meeting this challenge.

The study, “Electrode-Assisted Switching in Memristors Based on Single-Crystal Transition Metal Dichalcogenides,” published in ACS Applied Materials & Interfaces, shows how memristors—ultra-thin that “remember” past —switch their state with the help of electrodes and subtle atomic changes inside the material.

Atomic-level engineering enables new alloys that won’t break in extreme cold

Navigating the extreme cold of deep space or handling super-chilled liquid fuels here on Earth requires materials that won’t break. Most metals become brittle and fracture at such low temperatures. However, new research is pioneering an approach to build metal structures atom by atom to create tough and durable alloys that can withstand such harsh environments.

Traditional strengthening approaches are often not good enough for these applications. For example, a common heat treatment technique called precipitation hardening strengthens metals by creating tiny hard particles within their structure. But in , the materials can lose their ductility (the ability to bend, stretch or be pulled into a new shape without breaking) and fracture suddenly.

A study published in the journal Nature describes a new way to design so they stay strong and tough even at super low temperatures. The big idea is to create an alloy with two different types of perfectly arranged atomic structures inside it. These structures are called subnanoscale short-range ordering (SRO), which are tiny islands of organized atoms and nanoscale long-range ordering (NLRO), which are slightly larger.

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