For much of my career, I have been fascinated by the ways in which materials behave when we reduce their dimensions to the nanoscale. Over and over, I’ve learned that when we shrink a material down to just a few nanometers in thickness, the familiar textbook rules of physics begin to bend, stretch, or sometimes break entirely. Heat transport is one of the areas where this becomes especially intriguing, because heat is carried by phonons—quantized vibrations of the atomic lattice—and phonons are exquisitely sensitive to spatial confinement.
A few years ago, something puzzling emerged in the literature. Molecular dynamics simulations showed that ultrathin silicon films exhibit a distinct minimum in their thermal conductivity at around one to two nanometers thickness, which corresponds to just a few atomic layers. Even more surprisingly, the thermal conductivity starts to increase again if the material is made even thinner, approaching extreme confinement and the 2D limit.
This runs counter to what every traditional model would predict. According to classical theories such as the Boltzmann transport equation or the Fuchs–Sondheimer boundary-scattering framework, reducing thickness should monotonically suppress thermal conductivity because there is simply less room for phonons to travel freely and carry heat around. Yet the simulations done by the team of Alan McGaughey at Carnegie Mellon University in Pittsburgh insisted otherwise, and no established theory could explain why.
Last year, a research team led by UCLA achieved a milestone scientists had pursued for half a century. They succeeded in making radioactive thorium nuclei interact with light by absorbing and emitting photons, similar to how electrons behave inside atoms. First envisioned by the group in 2008, the breakthrough is expected to transform precision timekeeping and could significantly improve navigation systems, while also opening the door to discoveries that challenge some of the most basic constants in physics.
The advance comes with a major limitation. The required isotope, thorium-229, exists only as a byproduct of weapons-grade uranium, making it extremely rare. Researchers estimate that just 40 grams of this material are currently available worldwide for use in nuclear clock research.
A new study now shows a way around this obstacle. An international collaboration led by UCLA physicist Eric Hudson has developed an approach that uses only a small fraction of the thorium needed in earlier experiments, while delivering the same results previously achieved with specialized crystals. Described in Nature, the technique is both straightforward and low cost, raising the possibility that nuclear clocks could one day be small and affordable enough to fit into everyday devices like phones or wristwatches. Beyond consumer electronics, the clocks could replace existing systems used in power grids, cell phone towers, and GPS satellites, and may even support navigation where GPS is unavailable, such as in deep space or underwater.
Quantum computers will need large numbers of qubits to tackle challenging problems in physics, chemistry, and beyond. Unlike classical bits, qubits can exist in two states at once—a phenomenon called superposition. This quirk of quantum physics gives quantum computers the potential to perform certain complex calculations better than their classical counterparts, but it also means the qubits are fragile. To compensate, researchers are building quantum computers with extra, redundant qubits to correct any errors. That is why robust quantum computers will require hundreds of thousands of qubits.
Now, in a step toward this vision, Caltech physicists have created the largest qubit array ever assembled: 6,100 neutral-atom qubits trapped in a grid by lasers. Previous arrays of this kind contained only hundreds of qubits.
This milestone comes amid a rapidly growing race to scale up quantum computers. There are several approaches in development, including those based on superconducting circuits, trapped ions, and neutral atoms, as used in the new study.
The neutral-atom platform shows promise for scaling up quantum computers.
Researchers have discovered how to design and place single-photon sources at the atomic scale inside ultrathin 2D materials, lighting the path for future quantum innovations.
Like perfectly controlled light switches, quantum emitters can turn on the flow of single particles of light, called photons, one at a time. These tiny switches—the “bits” of many quantum technologies—are created by atomic-scale defects in materials.
Their ability to produce light with such precision makes them essential for the future of quantum technologies, including quantum computing, secure communication and ultraprecise sensing. But finding and controlling these atomic light switches has been a major scientific challenge—until now.
This study isolates extracellular vesicles and particles (EVPs) from hepatocellular carcinoma (HCC) cells. Biophysical and proteomic analyses demonstrate that sEVs and exomeres are distinctive entities. GALNS and MAN2B1 are identified as potential EM markers. HCC-derived EMs promote oncogenesis via several mechanisms, including PI3K/AKT/mTOR activation, cell cycle progression, and lipidomic dysregulation.
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The universe is full of a seemingly unending number of different things, from subatomic particles to plants and animals to gas giants and supernovae. But where did all of this stuff (for lack of a better word) come from? Let’s take a look.
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Boron, a chemical element next to carbon in the periodic table, is known for its unique ability to form complex bond networks. Unlike carbon, which typically bonds with two or three neighboring atoms, boron can share electrons among several atoms. This leads to a wide variety of nanostructures. These include boron fullerenes, which are hollow, cage-like molecules, and borophenes, ultra-thin metallic sheets of boron atoms arranged in triangular and hexagonal patterns.
Dr. Nevill Gonzalez Szwacki has developed a model explaining the variety of boron nanostructures. The analysis, published in the journal 2D Materials, combines more than a dozen known boron nanostructures, including the experimentally observed B₄₀ and B₈₀ fullerenes.
Using first-principles quantum-mechanical calculations, the study shows that the structural, energetic, and electronic properties of these systems can be predicted by looking at the proportions of atoms with four, five, or six bonds. The results reveal clear links between finite and extended boron structures. The B₄₀ cage corresponds to the χ₃ borophene layer, while B₆₅, B₈₀, and B₉₂ connect with the β₁₂, α, and bt borophene sheets, respectively. These structural links suggest that new boron cages could be created by using known two-dimensional boron templates.
Two-dimensional (2D) semiconductors are thin materials (i.e., one-atom thick) with advantageous electronic properties. These materials have proved to be promising for the development of thinner, highly performing electronics, such as fitness trackers and portable devices.
A 2D semiconductor that has attracted particular interest within the electronics community is molybdenum disulfide (MoS₂), a transition-metal dichalcogenide made up of one metal atom and two chalcogen atoms. To build reliable large-area electronics based on MoS₂ layers, engineers need to uniformly grow this material over wafer-scale surfaces, minimizing defects that hinder the performance of devices.
Researchers at the Institute for Basic Science (IBS), Pohang University of Science and Technology (POSTECH) and other institutes recently introduced a new approach to grow single-layer MoS₂ on substrates while maintaining a uniform atomic arrangement. Their approach, outlined in a paper in Nature Electronics, entails a greater control of the process by which small crystal regions merge on a substrate, also known as coalescence.