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Category: particle physics – Page 3
Ultracold atoms observed climbing a quantum staircase
For the first time, scientists have observed the iconic Shapiro steps, a staircase-like quantum effect, in ultracold atoms.
In a recent experiment, an alternating current was applied to a Josephson junction formed by atoms cooled to near absolute zero and separated by an extremely thin barrier of laser light. Remarkably, the atoms were able to cross this barrier collectively and without energy loss, behaving as if the barrier were transparent, thanks to quantum tunneling.
As the oscillating current flowed through the junction, the difference in chemical potential between the two sides did not change smoothly, but instead increased in discrete, evenly spaced steps, like climbing a quantum staircase. The height of each step is directly determined by the frequency of the applied current, and these step-like chemical potential differences are the atomic analog of Shapiro steps in conventional Josephson junctions.
Reversible spin splitting effect achieved in altermagnetic RuO₂ thin films
A research team affiliated with UNIST has made a advancement in controlling spin-based signals within a new magnetic material, paving the way for next-generation electronic devices. Their work demonstrates a method to reversibly switch the direction of spin-to-charge conversion, a key step toward ultra-fast, energy-efficient spintronic semiconductors that do not require complex setups or strong magnetic fields.
Led by Professor Jung-Woo Yoo from the Department of Materials Science and Engineering and Professor Changhee Sohn from the Department of Physics at UNIST, the team has experimentally shown that within the altermagnetic material ruthenium oxide (RuO₂), the process of converting spin currents into electrical signals can be precisely controlled and flipped at will.
This breakthrough is expected to accelerate the development of low-power devices capable of processing information more efficiently than current technologies. The study is published in the journal Nano Letters.
Raindrops form ‘sandballs’ as they roll downhill, contributing more to erosion than previously thought
What happens as a raindrop impacts bare soil has been fairly well-studied, but what happens to raindrops afterward is poorly understood. We know that the initial splash of raindrops on soil contributes to erosion, but a new study, published in the Proceedings of the National Academy of Sciences, finds that the journey of the raindrop downhill might have an even bigger impact on erosion than the initial splash.
Somewhere on the “Route de la Sorge” in Ecublens, Switzerland, members of the research team observed natural raindrops hitting the surface of a hillside and noticed that they collected particles of sand as they rolled downhill. This spurred the researchers to document the event with a camera and then take the idea to the lab.
In the lab, they constructed a 1.2 meter long bed covered with dry silicate sand and tilted at an angle of 30°. The lab conditions enabled the team to properly document the phenomenon by recording the evolution of the raindrops’ shapes as they rolled and take precise measurements of the relevant parameters. They found that each raindrop formed what they refer to as “sandballs” and that they took on differing shapes, depending on the conditions, and that the sandballs can move up to 10 times more soil than the initial splash alone.
Ultrafast fluorescence pulse technique enables imaging of individual trapped atoms
Researchers at the ArQuS Laboratory of the University of Trieste (Italy) and the National Institute of Optics of the Italian National Research Council (CNR-INO) have achieved the first imaging of individual trapped cold atoms in Italy, introducing techniques that push single-atom detection into new performance regimes.
By combining intense, microsecond-scale fluorescence pulses with fast re-cooling, the team demonstrated record-speed, low-loss imaging of individual ytterbium atoms—capturing clear single-atom signals in just a few microseconds while keeping more than 99.5% of the atoms trapped and immediately reusable.
This approach allows researchers to distinguish multiple atoms within a single optical tweezer without significant blurring, enabling precise onsite atom counting rather than the binary “zero-or-one” detection typical of existing methods. This capability is key for scaling neutral-atom quantum computers, advancing next-generation atomic clocks, and enhancing quantum simulators that probe complex many-body physics.
Rare Hall effect reveals design pathways for advanced spintronic materials
Scientists at Ames National Laboratory, in collaboration with Indranil Das’s group at the Saha Institute of Nuclear Physics (India), have found a surprising electronic feature in transitional metal-based compounds that could pave the way for a new class of spintronic materials for computing and memory technologies.
Spintronics, a field that harnesses the spin of electrons in addition to their charge, promises breakthroughs in technologies such as brain-like computers and memory devices that retain data without power.
The unexpected feature was found in Mn₂PdIn, a Heusler compound—a type of alloy valued for its tunable magnetic and electronic properties. These alloys can exhibit behaviors not seen in their individual elements, making them prime candidates for spintronic applications.
First beta-delayed neutron emission observed in rare fluorine-25 isotope
A research team at the Facility for Rare Isotope Beams (FRIB) is the first ever to observe a beta-delayed neutron emission from fluorine-25, a rare, unstable nuclide. Using the FRIB Decay Station Initiator (FDSi), the team found contradictions in prior experimental findings. The results led to a new line of inquiry into how particles in exotic, unstable isotopes remain bound under extreme conditions. Led by Robert Grzywacz, professor of physics at the University of Tennessee, Knoxville (UTK), the team included Jack Peltier, undergraduate student at UTK, Zhengyu Xu, postdoctoral researcher at UTK, Sean Liddick, professor of chemistry at FRIB and interim chairperson of MSU’s Department of Chemistry, and Rebeka Lubna, scientist at FRIB.
The team published its results in Physics Letters B.
“The different results on decay lifetime we obtained for fluorine-25 were similar to previously measured decay of oxygen-24. And while we are not entirely certain why we found this difference between previously published results, we have conducted numerous checks on our results and are confident in our findings,” Grzywacz said.