Scientists have shattered the diffraction limit, using continuous-wave lasers to resolve images at 0.1 nanometers.
Category: particle physics – Page 11
The weird rules of temperature get even stranger in the quantum realm
Can a single particle have a temperature? It may seem impossible with our standard understanding of temperature, but columnist Jacklin Kwan finds that it’s not exactly ruled out in the quantum realm.
By Jacklin Kwan
This ultra-thin surface controls light in two completely different ways
The team then fine-tuned the resonant strength of the meta-atoms to independently adjust the group delay for each spin. At the same time, frequency tuning and local structural rotation were used to set the phase while keeping unwanted crosstalk low. The PB phase, added through global rotation, extends the available phase range toward a full 2π without significantly altering the group delay design. Together, these elements create a practical single-layer design strategy for dual-spin achromatic control.
Experimental Proof Across Multiple Frequency Bands
The researchers demonstrated their approach experimentally using two types of devices operating in the 8–12 GHz range. One class consisted of spin-unlocked achromatic beam deflectors that maintained stable, spin-dependent steering across the band. The other involved achromatic metalenses that assigned different focusing functions to RCP and LCP light while preserving strong performance over a broad frequency range.
Into the neutrino fog: The ghosts haunting our search for dark matter
Ciaran O’Hare scribbles symbols using colored markers across his whiteboard like he’s trying to solve a crime—or perhaps planning one. He bounces around the edges of the board, slowly filling it with sharp angles and curling letters. I watch on, and when he senses I’m losing track, he pauses intermittently, allowing my brain to catch up. Ciaran speaks with an easy to understand British inflection, but the language on the whiteboard might as well be hieroglyphics.
Ciaran’s whiteboard doesn’t lay out a crime, but a mystery in the language of physics. In plain language, the mystery goes like this: everything we can see—with our eyes or elaborate telescopes—makes up only around 5% of the matter in our universe. There’s an invisible something out there that seems to bind the fabric of spacetime together. We don’t know what it is, but we know it’s there because of the force it exerts on the things we can see such as gigantic galaxies. The “something” is a phantom presence that touches our reality.
Scientists call it dark matter.
A ‘crazy’ dice proof leads to a new understanding of a fundamental law of physics
Right now, molecules in the air are moving around you in chaotic and unpredictable ways. To make sense of such systems, physicists use a law known as the Boltzmann distribution, which, rather than describe exactly where each particle is, describes the chance of finding the system in any of its possible states. This allows them to make predictions about the whole system even though the individual particle motions are random. It’s like rolling a single die: Any one roll is unpredictable, but if you keep rolling it again and again, a pattern of probabilities will emerge.
Developed in the latter half of the 19th century by Ludwig Boltzmann, an Austrian physicist and mathematician, this Boltzmann distribution is used widely today to model systems in many fields, ranging from AI to economics, where it is called “multinomial logit.”
Now, economists have taken a deeper look at this universal law and come up with a surprising result: The Boltzmann distribution, their mathematical proof shows, is the only law that accurately describes unrelated, or uncoupled, systems.
VIP-2 experiment narrows the search for exotic physics beyond the Pauli exclusion principle
The Pauli exclusion principle is a cornerstone of the Standard Model of particle physics and is essential for the structure and stability of matter. Now an international collaboration of physicists has carried out one of the most stringent experimental tests to date of this foundational rule of quantum physics and has found no evidence of its violation. Using the VIP-2 experiment, the team has set the strongest limits so far for possible violations involving electrons in atomic systems, significantly constraining a range of speculative theories beyond the Standard Model, including those that suggest electrons have internal structure, and so-called “Quon models.” Their experiment was reported in Scientific Reports in November 2025.
Austrian-Swiss physicist Wolfgang Pauli outlined the exclusion principle in 1925. It states that two identical “fermions” (a class of particles that includes electrons) cannot occupy the same quantum state. It explains why electrons fill atomic shells, why solids have rigidity, and why dense objects such as white dwarf stars do not collapse under gravity.
However, since its inception, physicists have been searching for signs that the Pauli exclusion principle may be violated in extreme conditions. “If the Pauli exclusion principle were violated, even at an extremely small level, the consequences would cascade from atomic physics all the way to astrophysics,” says FQxI member and physicist Catalina Curceanu of the Italian National Institute for Nuclear Physics (INFN), in Frascati, who is the spokesperson of the VIP-2 collaboration.
Experiments bring Enceladus’ subsurface ocean into the lab
Through new experiments, researchers in Japan and Germany have recreated the chemical conditions found in the subsurface ocean of Saturn’s moon, Enceladus. Published in Icarus, the results show that these conditions can readily produce many of the organic compounds observed by the Cassini mission, strengthening evidence that the distant world could harbor the molecular building blocks of life.
Beneath its thick outer shell of ice, astronomers widely predict that Saturn’s sixth largest moon hosts an ocean of liquid water in its south polar region. The main evidence for this ocean is a water-rich plume which frequently erupts from fractures in Enceladus’ surface, leaving a trail of ice particles in its orbital paths which contributes to one of its host planet’s iconic rings.
Between 2004 and 2017, NASA’s Cassini probe passed through this E-ring and plume several times. Equipped with instruments including mass spectrometers and an ultraviolet imaging spectrograph, it detected a diverse array of organic compounds: from simple carbon dioxide to larger hydrocarbon chains, which on Earth are essential molecular precursors to complex biomolecules.
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.
Glimpsing the quantum vacuum: Particle spin correlations offer insight into how visible matter emerges from ‘nothing’
Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have uncovered experimental evidence that particles of matter emerging from energetic subatomic smashups retain a key feature of virtual particles that exist only fleetingly in the quantum vacuum. The finding offers a new way to explore how the vacuum—once thought of as empty space—provides important ingredients needed to transform virtual “nothingness” into the matter that makes up our world.
The research, just published in Nature, was carried out by the STAR Collaboration at Brookhaven’s Relativistic Heavy Ion Collider (RHIC), a DOE Office of Science user facility for nuclear physics research. The paper presents evidence of a significant correlation in particle spins—a built-in quantum property related to magnetism—among certain pairs of particles emerging from proton-proton collisions at RHIC.
The STAR scientists’ analysis directly links those correlations to the spin alignment of virtual quark-antiquark pairs generated in the quantum vacuum. In essence, the scientists say, RHIC’s collisions give those virtual particles the energetic boost they need to transform into the real particles detected by STAR.