Ultracold atoms have successfully mimicked a fundamental quantum effect normally found in electronic circuits.
Category: particle physics
A Twist Between Hidden Dimensions May Explain Mass
The masses of fundamental particles such as the Z and W bosons could have arisen from the twisted geometry of hidden dimensions, a new theoretical paper has demonstrated.
The work has outlined a way to bypass the Higgs field as the source of particle masses, offering a new tool for understanding how the Higgs field itself might have emerged, as well as a possible means of addressing some of the persistent gaps in the Standard Model of particle physics.
“In our picture,” says theoretical physicist Richard Pinčák of the Slovak Academy of Sciences, “matter emerges from the resistance of geometry itself, not from an external field.”
Large Hadron Collider finally explains how fragile matter forms
In collisions at CERN’s Large Hadron Collider, hotter than the Sun’s core by a staggering margin, scientists have finally solved a long-standing mystery: how delicate particles like deuterons and their antimatter twins can exist at all. Instead of forming in the initial chaos, these fragile nuclei are born later, when the fireball cools, from the decay of ultra-short-lived, high-energy particles.
Detecting the hidden magnetism of altermagnets
Altermagnets are a newly recognized class of antiferromagnets whose magnetic structure behaves very differently from what is found in conventional systems. In conventional antiferromagnets, the sublattices are linked by simple inversion or translation, resulting in spin-degenerate electronic bands. In altermagnets, however, they are connected by unconventional symmetries such as rotations or screw axes. This shift in symmetry breaks the spin degeneracy, allowing for spin-polarized electron currents even in the absence of net magnetization.
This unique property makes altermagnets exciting candidates for spintronic technologies, a field of electronics that utilizes the intrinsic spin of the electrons, rather than just their charge, to store and process information. As spins can flip or switch direction extremely quickly, materials that allow spin-dependent currents could enable faster and more energy-efficient electronic devices.
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.