Nanowerk November 29, 2022 Harnessing the full complexity of optical fields requires the complete control of all degrees of freedom within a region of space and time. An international team of researchers (USA – MIT, industry, State University of New York, Rochester Institute of Technology, ARL (Rome), UK, Canada) resolved this challenge with a programmable photonic crystal cavity array enabled by four key advances: (1) near-unity vertical coupling to high-finesse microcavities through inverse design; (2) scalable fabrication by optimized 300 mm full-wafer processing; (3) picometre-precision resonance alignment using automated, closed-loop ‘holographic trimming’; and (4) out-of-plane cavity control via a high-speed μLED […]
New kind of tropical cyclone identified in the Indian Ocean
Phys.org November 28, 2022 Researchers in Australia focused on the regional wind variability that controls the intensity of cold-water upwelling off Sumatra – a key feature of the Indian Ocean Dipole (IOD). Their analysis of daily atmospheric data revealed the existence of convectively triggered synoptic-scale atmospheric cyclones in the South-East Tropical Indian Ocean (SETIO). The northern branch of the cyclones corresponded to westerly equatorial wind events, whereas the eastern branch involved north-westerly winds that operate to suppress cold-water upwelling off Sumatra’s west coast. Data for the period 1988–2022 showed that 5–9 SETIO cyclones normally form each year during the boreal […]
Researchers develop highly CO-tolerant fuel cell anode catalyst
Phys.org November 29, 2022 Platinum on carbon (Pt/C) catalyst is commercially adopted in fuel cells but it undergoes active-site poisoning by carbon monoxide (CO) diminishing the device performances. Researchers in China incorporated cobalt (Co) into molybdenum-nickel alloy (MoNi4), termed Co-MoNi4, which not only shows superior hydrogen oxidation reaction activity over the Pt/C catalyst in alkali, but exhibits excellent CO tolerance with only small activity decay after 10 000 cycles. It yielded peak power density far exceeding the Pt/C catalyst. Experimental and computational studies revealed that weakened CO chemisorption originates from the electron-deficient Ni sites… read more. TECHNICAL ARTICLE
A scalable quantum memory with a lifetime over 2 seconds and integrated error detection
Phys.org November 28, 2022 Because of their long coherence times and efficient optical interface, color centers in diamond are promising candidates for quantum memory nodes. Researchers at Harvard University integrated two-qubit network node based on silicon-vacancy centers (SiVs) in diamond nanophotonic cavities. The qubit register consisted of the SiV electron spin acting as a communication qubit and the strongly coupled silicon-29 nuclear spin acting as a memory qubit with a quantum memory time exceeding 2 seconds. They demonstrated electron-photon entangling gates at temperatures up to 1.5 kelvin and nucleus-photon entangling gates up to 4.3 kelvin and efficient error detection in […]
Scientists construct novel quantum testbed one atom at a time
Phys.org November 29, 2022 A team of researchers in the US (Argonne National Laboratory, Old Dominion University) synthesized artificial graphene nanoribbons by positioning carbon monoxide molecules on a copper surface to confine its surface state electrons into artificial atoms positioned to emulate the low-energy electronic structure of graphene derivatives. They showed that the dimensionality of artificial graphene can be reduced to one dimension with proper “edge” passivation, with the emergence of an effectively gapped one-dimensional nanoribbon structure which showed evidence of topological effects analogous to graphene nanoribbons. They spatially explored robust, zero-dimensional topological states by altering the topological invariants of […]
Seeding the oceans with iron-rich fertilizer nanoparticles to store excess carbon dioxide
Nanowerk November 29, 2022 Artificial ocean fertilization (AOF) carbon sequestration efficiency appears lower than natural ocean fertilization processes due mainly to the low bioavailability of added nutrients, along with low export rates of AOF-produced biomass to the deep ocean. An international team of researchers (UK, Thailand, USA – University of South Carolina, industry, Pacific Northwest National Laboratory) explored the potential application of engineered nanoparticles (ENPs) to overcome these issues. Data from 123 studies showed that some ENPs may enhance phytoplankton growth at concentrations below those likely to be toxic in marine ecosystems. ENPs may also increase bloom lifetime, boost phytoplankton […]
Stripping carbon from the atmosphere might be needed to avoid dangerous warming—but it’s a deeply uncertain prospect
Phys.org November 25, 2022 The target to limit global warming to 1.5℃ this century remains but it is unlikely we’ll meet it. Attention is turning to other options for climate action, including large-scale carbon removal. Proponents argue carbon removal is required at a massive scale to avoid dangerous warming. However, successfully stripping carbon from the atmosphere at the scale our planet requires is a deeply uncertain prospect. The IPCC said in a report this year that large-scale deployment of carbon dioxide removal was “unavoidable” if the world is to reach net-zero greenhouse gas emissions. According to the IPCC report in […]
Transporting of two-photon quantum states of light through a phase-separated Anderson localization optical fiber
Phys.org November 23, 2022 Experiments in the past have demonstrated Anderson localization in optical fibers, classical or conventional light, in two dimensions while propagating it through the third dimension. An international team of researchers (Spain, USA – industry, Italy) engineered the optical setup to send the quantum light through the phase-separated Anderson localization fiber and detected its arrival with the single-photon avalanche diode (SPAD) array camera. It enabled them not only to detect and identify them as pairs, as they arrived at the same time. As the pairs are quantum correlated, knowing where one of the two photons is detected […]
Underwater tsunamis created by glacier calving cause vigorous ocean mixing
Phys.org November 24, 2022 Researchers in the UK took ocean measurements close to the William Glacier, situated on the Antarctic Peninsula. It has one or two large calving events per year, and the team estimated this one broke off around 78,000 square meters of ice. Before it broke away, the water temperature was cooler at around 50-100 meters in depth, and warmer below this. After the calving temperature was much more even across different depths. Glaciers that end up in the sea cause big waves at the surface and create waves inside the ocean causing the sea to mix. This […]
Using machine learning to infer rules for designing complex mechanical metamaterials
Phys.org November 23, 2022 Combinatorial problems arising in puzzles, origami, and (meta) material design have rare sets of solutions, which define complex and sharply delineated boundaries in configuration space. The boundaries are difficult to capture with conventional statistical and numerical methods. Researchers in the Netherlands have shown that convolutional neural networks can learn to recognize these boundaries for combinatorial mechanical metamaterials, down to the finest detail, despite using heavily undersampled training sets, and can successfully generalize. According to the researchers even if machine learning is typically a “black box” approach, it can still be very valuable for exploring the design […]