Toggle light / dark theme

How fast can a microlaser switch ‘modes?’ A simple rule reveals a power-law time scaling

Modern technologies increasingly rely on light sources that can be reconfigured on demand. Think of microlasers that can quickly switch between different operating states—much like a car shifting gears—so that an optical chip can route signals, perform computations, or adapt to changing conditions in real time. The microlaser switching is not a smooth, leisurely process, but can be sudden and fast. Generally, nearly identical “candidate” lasing states compete with each other in a microcavity, and the laser may abruptly jump from one state to another when external conditions are tuned.

This raises a practical question: How fast can such a switch be, in principle? For physicists, it raises a deeper one: Does the switching follow a universal rule, like other phase transitions in nature?

A team at Peking University has now provided a clear picture of an ultrahigh-quality microcavity laser—the time the laser needs to complete a state switch follows a remarkably simple power-law rule. When the control knob is swept faster, the switch becomes faster—but not arbitrarily so. Instead, the switching time decreases with the square root of the sweep speed, corresponding to a robust exponent close to half. This result effectively sets a speed limit for how quickly such microlasers can “change gears.” The findings are published in Physical Review Letters.

Humidity-resistant hydrogen sensor can improve safety in large-scale clean energy

Wherever hydrogen is present, safety sensors are required to detect leaks and prevent the formation of flammable oxyhydrogen gas when hydrogen is mixed with air. It is therefore a challenge that today’s sensors do not work optimally in humid environments—because where there is hydrogen, there is very often humidity. Now, researchers at Chalmers University of Technology, Sweden, are presenting a new sensor that is well suited to humid environments—and actually performs better the more humid it gets.

“The performance of a hydrogen gas sensor can vary dramatically from environment to environment, and humidity is an important factor. An issue today is that many sensors become slower or perform less effectively in humid environments. When we tested our new sensor concept, we discovered that the more we increased the humidity, the stronger the response to hydrogen became. It took us a while to really understand how this could be possible,” says Chalmers doctoral student Athanasios Theodoridis, who is the lead author of the article published in the journal ACS Sensors.

Hydrogen is an increasingly important energy carrier in the transport sector and is used as a raw material in the chemical industry or for green steel manufacturing. In addition to water being constantly present in ambient air, it is also formed when hydrogen reacts with oxygen to generate energy, for example, in a fuel cell that can be used in hydrogen-powered vehicles and ships. Furthermore, fuel cells themselves require water to prevent the membranes that separate oxygen and hydrogen inside them from drying out.

Stabilized iron catalyst could replace platinum in hydrogen fuel cells

Japan and California have embraced hydrogen fuel-cell technologies, a form of renewable energy that can be used in vehicles and for supplying clean energy to manufacturing sectors. But the technology remains expensive due to its reliance on precious metals such as platinum. Engineers at Washington University in St. Louis are working on this challenge, finding ways to stabilize ubiquitous iron components for use in fuel cells to replace the expensive platinum metals, which would make hydrogen fuel-cell vehicles more affordable.

Cost challenges for fuel-cell vehicles

“The hydrogen fuel cell has been successfully commercialized in Japan and California in the U.S.,” said Gang Wu, a professor of energy, environmental and chemical engineering at the McKelvey School of Engineering. “But these vehicles struggle to compete with the battery vehicle and combustion engine vehicle, with cost being the main issue.”

Electronic Chirality Without Structural Chirality

The handedness or chirality of a golf club, a baseball glove, or certain crystal lattices is plain to see: Their structures are such that one cannot be overlaid on its mirror image. Now Takayuki Ishitobi of the Japan Atomic Energy Agency and Kazumasa Hattori of Tokyo Metropolitan University have discovered that a crystal whose atomic structure is achiral can still host a chiral electronic state, which they dub purely electronic chirality (PEC) [1].

Four years ago, theorists found that the chirality of a crystalline structure can be quantified with a single number G0, which is given by the inner product of polar and axial vectors. The polar one is the electric dipole moment. The axial one is the electric toroidal dipole, which quantifies the geometric relationship between the electrons’ spin and orbital axes, and which is present in a few crystals with the requisite intricate arrangement of orbitals. Ishitobi and Hattori sought crystals whose atomic structures were achiral, but in which electronic interactions could induce an electric toroidal dipole and, therefore, a nonzero G0.

In some crystals, the conduction electrons occupy 2D planes. Ishitobi and Hattori realized that, if such a crystal also possesses atoms with electric quadrupole moments, the internal electric field could couple these quadrupoles to the electric toroidal dipole. A PEC would arise if the electric quadrupole has a specific arrangement and if the crystal has a certain lattice structure. From their calculations, the researchers determined that the intermetallic compound uranium rhodium stannide ticks all the boxes. They also found that the adoption of PEC by this material’s electrons could account for an unexplained phase transition at a temperature of 54 K.

CATL unveils battery with 12-minute charging and 1.5 million mile life

The company is already the world’s largest battery maker, supplying cells to major automakers. With this latest development, the battery giant is positioning itself at the center of the race to deliver gasoline-like convenience without sacrificing durability.

The core challenge engineers set out to address was whether an EV battery could withstand repeated ultra-fast charging without rapid degradation. A 5C charge rate means an 80-kilowatt-hour battery pack could theoretically accept around 400 kilowatts of power. That level of charging can refill a battery in roughly 12 minutes, similar to a typical gas stop.

Fast charging has long been associated with faster wear. The engineers tested whether the chemistry could handle that stress over time. According to the company, the answer was yes. Under standard conditions at 68°F, the battery retained at least 80 percent of its original capacity after 3,000 full charge-and-discharge cycles.

The Hot Mess of AI: How Does Misalignment Scale with Model Intelligence and Task Complexity?

When AI systems fail, will they fail by systematically pursuing the wrong goals, or by being a hot mess? We decompose the errors of frontier reasoning models into bias (systematic) and variance (incoherent) components and find that, as tasks get harder and reasoning gets longer, model failures become increasingly dominated by incoherence rather than systematic misalignment. This suggests that future AI failures may look more like industrial accidents than coherent pursuit of a goal we did not train them to pursue.

Using complex networks to tame combustion instability

Engineers have long battled a problem that can cause loud, damaging oscillations inside gas turbines and aircraft engines: combustion instability. These unwanted pressure fluctuations create vibrations so intense that they can cause fatal structural damage to combustor walls, posing a serious threat in many applications. Combustion instability occurs when acoustic waves, heat release, and flow patterns interact in a strong feedback loop, amplifying each other until the entire system becomes unstable.

The complex interaction has made it difficult to predict when and where dangerous oscillations will emerge. This challenge has motivated researchers to seek new analytical frameworks that can capture the key driving regions of combustion instability.

Now, a research team led by Professors Hiroshi Gotoda from Tokyo University of Science and Ryoichi Kurose from Kyoto University, Japan, has developed an innovative approach using network science to understand and suppress combustion instability. Their paper, published in the journal Physical Review Applied on July 1, 2025, applies complex network analysis to spray combustion instability in a backward-facing step combustor.

OpenClaw Bug Enables One-Click Remote Code Execution via Malicious Link

A high-severity security flaw has been disclosed in OpenClaw (formerly referred to as Clawdbot and Moltbot) that could allow remote code execution (RCE) through a crafted malicious link.

The issue, which is tracked as CVE-2026–25253 (CVSS score: 8.8), has been addressed in version 2026.1.29 released on January 30, 2026. It has been described as a token exfiltration vulnerability that leads to full gateway compromise.

“The Control UI trusts gatewayUrl from the query string without validation and auto-connects on load, sending the stored gateway token in the WebSocket connect payload,” OpenClaw’s creator and maintainer Peter Steinberger said in an advisory.

/* */