A Jupiter-sized world just 7.5 light-years away is cloudy, chemically complex and, it turns out, more like home than anyone expected. Using the James Webb Space Telescope, Brittany Miles, assistant astronomer at the University of Arizona’s Steward Observatory, led a team that spent 11 hours staring at WISE 0855, the coldest known brown dwarf, collecting a spectrum of its light every 15 minutes.
Many fascinating phases in quantum materials emerge when electrons, atoms and other microscopic components begin to act collectively. But these phases do not necessarily appear out of nowhere when a material crosses a transition temperature. Before long-range order develops, microscopic fluctuations can already be present.
Understanding these precursor fluctuations is important because they can tell us which interactions are responsible for driving a material toward an emergent phase. However, the difficulty is seeing them.
Most experimental signatures of phase transitions are easiest to recognize once long-range order has already formed. For example, we can look for a new periodic structure in a diffraction experiment. However, fluctuations that precede this order are transient and lack the same well-defined spatial pattern, making them much harder to measure directly.
Finding a single cancer cell in a tube of blood is a bit like finding a needle in a haystack. As researchers seek to detect ever-smaller and rarer targets, from viruses to circulating tumor cells in blood, the demand for ultrasensitive, robust sensors that are practical for real-world samples continues to grow.
A major challenge is doing this without adding fluorescent tags or other labels. Most label-free optical sensors work only when the targets pass extremely close to or bind to a tiny sensing area on the device. At low concentrations, many particles never hit that spot, and even when they do, their signals can be drowned out by background noise, limiting detection efficiency and making rare targets especially difficult to find.
This limitation is shared by many optical microsensors, including whispering-gallery-mode (WGM) resonators, among the most sensitive optical sensors ever developed. These devices can detect individual nanoparticles and molecules with exceptional precision, but their sensing region is typically confined to a very small area close to the sensor surface.
Scientists have created a new family of materials whose behavior can be tuned by changing their metallic “recipe”—opening new possibilities for uses including gas storage and sensing.
Led by the University of Birmingham, chemists have created a highly adaptable metal-organic framework (MOF), in which metal atoms are connected by organic molecules to create highly ordered structures containing tiny pores.
Publishing their discovery in Angewandte Chemie, the team has shown that changing the proportions of metals within the material can alter properties including magnetism, porosity, light absorption and CO₂ uptake.
For highly fragile quantum information systems, the ability to store quantum information is vital—but also challenging. Quantum information is transported in particles of light called photons, which often must be temporarily paused (or “stored”) while other, slower quantum operations catch up. This storage must be performed on microchips as small as 1 centimeter (0.4 inches)—a distance covered by light in a few trillionths of a second. Storing photons for a microsecond would represent a massive leap forward for the capabilities of quantum chips.
New research from The Grainger College of Engineering at the University of Illinois Urbana-Champaign addresses this challenge by developing an integrated on-chip nanophotonic platform for longer-term storage of photons.
The research, led by physics professor Elizabeth Goldschmidt and published in Nano Letters, describes an integrated platform that leverages the versatility of spectral hole burning and the scalability of thin-film lithium niobate, giving it potential for scalable manufacturing, with implications for both classical and quantum photonics.
Watermarks are increasingly being used to make AI-generated images recognizable and to ensure their origin can be traced. Previous research has focused on whether watermarks can withstand image manipulation. CISPA researcher Michel Meintz from the SprintML Lab has investigated whether watermarks can withstand the training of a new generative model.
The result: Not all watermarks are equally robust. Their ability to persist across multiple model generations depends heavily on their design and the model that is used. The paper “Watermark Degradation Across Model Iterations” was presented at the ACM Workshop on Information Hiding and Multimedia Security (IH&MMSec 26) in Florence.
AI-generated images are ubiquitous today and are widely distributed, especially via the internet. This increases the risk that AI-generated images will be used to train new image-generation models. “When companies train on their own synthetic data, it can lead to model collapse,” explains Michel Meintz. “The more you train on your own synthetic data, the more likely the model’s quality is to deteriorate.”
Artificial intelligence is increasingly becoming part of our everyday lives, from digital assistants to robots that respond to their surroundings. Each of these capabilities is based on physical computational processes that consume energy. An international research team led by Hans Briegel from the Department of Theoretical Physics at the University of Innsbruck, Austria, has investigated the physical limits on the efficiency with which intelligent systems process information. Their findings are published in Physical Review X.
An agent is a system that gathers information from its environment and responds to that feedback, much like a robot moving through a room while constantly making new observations. “Through his actions, the agent changes the world he himself is trying to predict. We wanted to understand what that changes about the physics of information processing,” explains Lukas Fiderer, the study’s lead author.
In 1961, physicist Rolf Landauer identified a fundamental physical cost of erasing information. However, the relationship also works in reverse: Under suitable conditions, an agent can use information about a physical system to extract energy from it. The new study investigates the greatest average amount of useful energy an ideal agent can extract per interaction through repeated exchanges with its environment. It thus provides a precise thermodynamic benchmark for comparing different ways of organizing the agent’s memory and actions.
University of Glasgow researchers are part of an international collaboration that could lead to a new generation of quantum sensors. The team, which included researchers from the University of Tokyo, University of Glasgow, University of Sheffield and Kobe University, has for the first time used light to read out the magnetic spin of electrons trapped inside a porous crystalline material known as a metal-organic framework (MOF).
The team’s work builds on previous research into a method of detecting electron spins using light called optically detected magnetic resonance, or ODMR. The technique has attracted attention as a useful method for reading out spin qubits in quantum sensing.
The development marks an important step toward using MOFs, which have been regarded as promising materials for quantum sensing applications, to detect chemical substances with extraordinary sensitivity in future sensing devices.
A study of twisted two-dimensional semiconductors reveals how subtle material disorder can emerge at different spatial scales.
Two distinct forms of hidden disorder may influence how ultrathin semiconductors emit light. One extends across relatively large areas of the material, while the other is concentrated around tiny defects. A new theoretical approach offers a way to identify these patterns by analyzing changes in light emission rather than attempting to separate individual spectral signals.
Developed by Katsunori Wakabayashi at the Research Center for Materials Nanoarchitectonics (MANA), part of the National Institute for Materials Science (NIMS), the framework could provide a more reliable way to investigate imperfections in materials used for advanced optical and quantum devices.
Researchers have discovered that fire salamanders can produce a striking cyan-green fluorescence when exposed to ultraviolet light.
Fire salamanders are famous for their vivid yellow and black warning colors, but part of their appearance remains invisible to human eyes. Researchers have found that when ultraviolet light strikes the animals, their skin and defensive secretions emit a cyan-green fluorescence that may persist for more than 24 hours after the secretions are released.
The fluorescence is strongest in the salamanders’ yellow underside and along the sides of the body. It originates mainly from skin glands and the substances they produce, suggesting that the phenomenon is closely connected to the same tissues involved in the animal’s chemical defenses.