Phys.org November 1, 2022 When measuring with light, the lateral extent of the structures that can be resolved by an optical imaging system is fundamentally diffraction limited. Researchers in Germany have developed an approach that uses microspheres placed directly on the surface of the object to extend the limits of interferometric topography measurements for optical resolution of small structures. They identified microspheres and photonic nanojets to explain the resolution enhancement. They extended the model with respect to microsphere-assisted interference microscopy providing a rigorous simulation of the scattered electric field directly above the sphere. Simulation and experimental results were compared in […]
Physicists see light waves moving through a metal
Nanowerk October 27, 2022 With the discovery of nodal-line semimetals, the notion of the Dirac point has been extended to lines and loops in momentum space. However, experimental evidence for the enhanced correlations in nodal-line semimetals is sparse. An international team of researchers (USA -Columbia University, University of Arkansas, Pennsylvania State University, Florida State University, National High Magnetic Field Laboratory, Flatiron Institute, China, the Netherlands, Germany) found prominent correlation effects in a nodal-line semimetal compound, ZrSiSe, through experiments and density functional theory calculations. They observed two fundamental spectroscopic hallmarks of electronic correlations: strong reduction of the free-carrier Drude weight and […]
Quantum dots form ordered material
Science Daily November 1, 2022 It is possible to accurately design the electronic properties of quantum dots just by changing their size. However, to create functional devices, many dots have to be combined into a new material. During this process, the properties of the dots are often lost. Researchers in the Netherlands have made a highly conductive optoelectronic metamaterial through controlled ordering of colloidal quantum dots in three dimensions and over large areas achieving outstanding transport properties. The measured electron mobilities are the highest ever reported for a self-assembled solid of fully quantum-confined objects. This ultimately demonstrated that optoelectronic metamaterials […]
Researchers design next-generation electrolytes for lithium batteries
Nanowerk October 29, 2022 The lithium-metal batteries cycling encounters a low Coulombic efficiency (CE) due to the unceasing electrolyte decomposition. Improving the stability of solid electrolyte interphase (SEI) suppresses the decomposition and increases CE. However, SEI morphology and chemistry alone cannot account for CE, and a full explanation is still lacking. Researchers in Japan found that in diverse electrolytes, the large shift in the Li electrode potential and its association with the Li+ coordination structure influences the CE. Machine learning regression analysis and vibrational spectroscopy revealed that the formation of ion pairs is essential for upshifting the Li electrode potential, […]
Revolutionary technique to generate hydrogen more efficiently from water
Phys.org October 27, 2022 Typically, electron transfer proceeds solely through either a metal redox chemistry or an oxygen redox chemistry without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway. An international team of researchers (Singapore, USA – Brookhaven National Laboratory, China) has discovered an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. The proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states with […]
Scientists discover material that can be made like a plastic but conducts like metal
Science Daily October 26, 2022 An international team of researchers (USA – University of Chicago, Stony Brook University, Argonne National Laboratory, South Korea) discovered a way to create a material that can be made like a plastic but conducts electricity more like a metal when they strung nickel atoms like pearls into a string of molecular beads made of carbon and sulfur. The material easily and strongly conducted electricity when heated or chilled or exposed to air and humidity, or even dripped acid and base. But the most striking thing was that the molecular structure of the material was disordered. […]
Stable sodium anodes for sodium metal batteries
Phys.org November 2, 2022 All-solid-state batteries are disadvantaged by their poor physical solid-solid interfacial contact and low ionic conductivity, which restrict their performance and hinder their short-term commercial applicability. Based on the interfacial protection strategy, researchers at UT Austin introduced fluoroethylene carbonate (FEC) into the PDOL system (1,3-Dioxolane (DOL) that can be polymerized through catatonically ring-opening reactions at room temperature to obtain poly(1,3-dioxolane). After the introduction of FEC, the accumulation of reaction products was reduced at the Na metal anode side prior to DOL addition, forming a NaF-rich passivation layer and inhibiting further side reactions between DOL and the Na […]
Study urges caution when comparing neural networks to the brain
MIT News November 2, 2022 The central claims of recent deep learning-based models of brain circuits are that they make novel predictions about neural phenomena or shed light on the fundamental functions being optimized. Through the case-study of grid cells in the entorhinal-hippocampal circuit, a team of researchers in the US (Stanford University, MIT) showed that one often gets neither. They reviewed the principles of grid cell mechanism and function obtained from analytical and first-principles modeling efforts and examined the claims of deep learning models of grid cells. Using large-scale hyperparameter sweeps and theory-driven experimentation, they demonstrated that the results […]
Unipolar quantum optoelectronic devices: Higher speeds in free-space optical communications in the midinfrared band
Phys.org November 2, 2022 A recently demonstrated proof-of-concept of high-speed transmission taking advantage of intersubband devices was limited by the short-distance optical path (up to 1 m). An international team of researchers (France, USA -University of Central Florida, University of New Mexico) used an uncooled quantum cascade detector and a nitrogen-cooled quantum well-infrared photodetector to study the possibility of building a long-range link using unipolar quantum optoelectronics. They evaluated the maximum data rate of their link in a back-to-back configuration before adding a Herriott cell to increase the length of the light path up to 31m. By using pulse shaping, […]
Universal parity quantum computing, a new architecture that overcomes performance limitations
Phys.org October 28, 2022 Researchers in Austria have developed a universal gate set for quantum computing with all-to-all connectivity and intrinsic robustness to bit-flip errors based on parity encoding. They showed that logical controlled phase gate and Rz rotations can be implemented in parity encoding with single-qubit operations. Together with logical Rx rotations, implemented via nearest-neighbor controlled-NOT gates and an Rx rotation, these form a universal gate set. As the controlled phase gate requires only single-qubit rotations, the proposed scheme has advantages for several cornerstone quantum algorithms, e.g., the quantum Fourier transform. They presented a method to switch between different […]