The physics desk
Physics from the quantum to the cosmos: particle physics, quantum computing, astrophysics, cosmology and the discoveries that change what is possible.
The clock's frequency is pinned down to an uncertainty of one part in 10 quintillion, the lowest for any optical clock, and two copies agreed more closely than any clocks ever compared. Its secret is an atom that barely notices heat or magnetism.
South Africa's MeerKAT telescope traced repeating radio bursts to the giant planet Beta Pictoris b, 64 light-years away. The signal shows its magnetic field is at least 1,250 gauss, far stronger than Jupiter's.
Galaxies whose brightness differs 400,000-fold share nearly the same central dark matter surface density. A Sejong University physicist derived 170 solar masses per square parsec from gravity alone, inside the observed range.
If dark matter is made of ultralight particles that ripple like waves, those ripples should shift the multiple images of a distant quasar. The simulations matched a real lensed quasar better than standard models.
Tidal disruption events compress a supermassive black hole's feeding cycle from millennia into years. A Curtin-IAS team found the delayed radio jets, arriving hundreds to thousands of days after a star is torn apart, switch on at the same threshold known from X-ray binaries in our galaxy. 'The physics does not seem to care how big they are.'
The Erlangen, Munich, Technion and Central Florida team reports in Nature Physics that it can set the size and direction of the current by adjusting the polarization and timing of the two beams, the first time anyone has controlled electrons within a light-made Floquet state rather than just observing it.
The Science paper from Sebastian Will's lab and theorist Tijs Karman reports the suppression was so complete that only an upper bound, set by how long a single molecule survives, could be measured. It opens the door to 'strongly dipolar quantum liquids.'
Older theories said the clusters would grow forever and the liquid would suddenly lock up. Adding that feedback loop to the equations made the sharp transition vanish and matched the supercomputer simulations almost perfectly. The same physics may describe tumor cells that get stuck and then start invading.
Stefano Profumo applied the Barbieri-Giudice fine-tuning measure, which asks how wildly a model's prediction swings when you nudge one input, to WIMPs, Higgs-portal particles and several ways the early universe could have made black holes. 'The tuning lives in the specific model, not in the kind of dark matter you started with.'
The Nature Materials paper from Vinod Menon's group is the first demonstration of microwave-to-optical transduction through magnon-exciton coupling. It does not yet move single quantum states, but it works in a bulk crystal that can be thinned to a few atomic layers.
The UC Santa Barbara team used a new 'phase-space distance' method with a supervised machine-learning classifier for the first time in a particle search and showed it beats the standard sphericity test. 'It's not a dead end,' said graduate student Danyi Zhang. 'If this thing existed with these properties, we'd have seen it.'
The result backs a long-suspected 'universal' reconnection rate and says the speed is set inside the thin current sheet, not by the plasma feeding it. Better reconnection models mean better space weather forecasts for satellites and power grids.
The Science paper shows why the effect was missed: the simplified models everyone used, like Kuramoto, strip out the very dynamics that let disorder stabilize a network. It may also explain why huge, diverse ecosystems don't collapse the way 1970s math says they should.
Neither long-range magnetic order nor ferroelectric order survives easily in a sheet a few atoms thick, and getting both to coexist at 19°C was thought to be extraordinarily hard. Cheng Gong's team did it by building each order in its own layer and pressing the layers together.
Scanning 3D X-ray diffraction at the upgraded European Synchrotron showed a lanthanum cuprate divided into orthorhombic and tetragonal regions with boundaries hundreds of times wider than expected. The team says those boundaries likely fight superconductivity and that bulk measurements will need reinterpreting.
The Károlyházy model held that tiny ripples in spacetime erode quantum superpositions and explain why big objects behave classically. The VIP collaboration at Gran Sasso says the predicted signal isn't there, and the null result narrows where quantum gravity can hide.
Quantum jumps were seen in trapped ions in 1986 and in photons in 2007. Sound took another 19 years. The team paired a chip-scale resonator with a superconducting qubit that checked hundreds of times whether one phonon was still there.
The National University of Singapore team used 0.14-terahertz radiation, whose photons carry just 0.6 millielectronvolts, to warm the charge carriers and nothing else. The trick separates two effects that every conventional measurement blurs together.
Two 900-pound 'disco ball' satellites launched in 1976 and 1992 have tracked the geocenter for decades, but the last two official estimates disagreed by 7 millimeters, nearly the size of the motion itself. A new JPL method cuts the error to fractions of an inch.
The Nature paper published Wednesday describes the March road test and the next goal: a 10-hour trip from Geneva to Düsseldorf, where a magnetically quiet lab could compare protons and antiprotons 100 times more precisely than CERN can.
The team set three records at once for circular Rydberg atoms, giant atoms that are the leading candidates for neutral-atom quantum computers. The trick was two transparent conductive plates that block the room's own microwave glow, an idea from the 1980s.
For decades 'slide electrification' has been blamed entirely on ions swapping at the liquid-solid boundary. The new Nature Physics experiments show electrons must also be jumping directly, a process previously thought to happen only when two solids rub.
Alain Goriely traced the story to Vitruvius, writing four centuries after the temple was finished, and found 'insufficient historical evidence and no scientific evidence' that any of a dozen claimed refinements corrects anything a human can see.
The trick is a backward-then-forward lurch of the whole body timed to the gate release. The model says the same rider could legally leave the line at 1.3 m/s, more than three times faster.
It is the first experimental realization of ideal Amontons-Coulomb friction. Electron microscopes traced the speed dependence to wave-like crystal flaws called ripplocations, which disappear at high temperature.
A Lancaster-led team matched timetables, newspapers, sunspot logs and aurora reports to move the geomagnetic storm from October 18, 1841 to October 18, 1848. The earliest real case is now a March 1847 telegraph failure.
Marko Lončar's lab 'dressed' a silicon-vacancy spin with phonons instead of microwave pulses. The technique works inside the phononic cavities that would link nodes of a chip-scale quantum network, letting sound do both jobs at once.
ESA's HENON mission, carrying the Imperial College MAGIC magnetometer, launches in early 2027 into a distant retrograde orbit far beyond the L1 point. Its lead scientist calls it 'a step change' and a pathfinder for the larger SHIELD mission.
Reported in Physical Review Letters, the trick is timing: match the speed of the atoms' motion to the length of the light pulse they emit together, and up to 89% of the light goes one direction. No mirrors, no lattice, no chiral structure required.
The equivalence principle has only ever been tested on ordinary matter. Muons live 2.2 microseconds, so the ETH Zurich team turned helium's chemical potential into an 'atomic cannon.' If muonium falls differently, it could point to a fifth force.