Phys.org August 14, 2024 Toroidal electromagnetic pulses have been recently reported as non-transverse, space-time non-separable topological excitations of free space. However, their propagation dynamics and topological configurations have not been comprehensively experimentally characterized. The existing generators were limited in optical and terahertz domains; however, the feasibility and significance of generating such pulses at microwave frequencies have been overlooked. An international team of researchers (USA – Illinois Institute of Technology, China, Singapore) found that microwave toroidal pulses could be launched by a transient finite-aperture broadband horn antenna emitter, as an electromagnetic counterpart of “air vortex cannon.” Using this generator, they experimentally […]
First-of-its-kind analysis reveals importance of storms in air–sea carbon exchange in Southern Ocean
Phys.org August 14, 2024 The strength and variability of the Southern Ocean carbon sink is a significant source of uncertainty in the global carbon budget. One barrier to reconciling observations and models is understanding how synoptic weather patterns modulate air-sea carbon exchange. An international team of researchers (USA – Monterey Bay Aquarium Research Institute, NCAR, Pacific Marine Environmental Laboratory, University of Arizona, Canada, South Africa) identified and tracked storms using atmospheric sea level pressure fields from reanalysis data to assess the role that storms play in driving air-sea CO2 exchange. They examined the main drivers of CO2 fluxes under storm […]
MIT researchers use large language models to flag problems in complex systems
MIT News August 14, 2024 The flexible nature of large language models (LLMs) allows them to be used for many applications. A team of researchers in the US (MIT, industry) used LLMs for challenging task time series anomaly detection. They addressed two aspects novel for LLMs: the need for the model to identify part of the input sequence (or multiple parts) as anomalous; and the need for it to work with time series data rather than the traditional text input. Their framework included a timeseries-to-text conversion module, as well as end-to-end pipelines that prompt language models to perform time series […]
A new approach to fine-tuning quantum materials
MIT News August 12, 2024 For topological Weyl semimetals, there is a pressing need to fine-tune the Fermi level, a critical aspect of quantum materials, to the Weyl nodes and unlock exotic electronic and optoelectronic effects associated with the divergent Berry curvature. However, the situation for bulk crystals poses significant challenges. A team of researchers in the US (MIT, Brookhaven National Laboratory, industry) demonstrated the meV level ultra-fine-tuning of the Fermi level of bulk topological Weyl semimetal tantalum phosphide. By calculating the desired carrier density and controlling the accelerator profiles, the Fermi level could be experimentally fine-tuned from 5 meV below, […]
New method paves the way for cost-effective and high-efficiency green hydrogen production
Phys.org August 13, 2024 Hydrogen production through anion-exchange membrane water electrolyzers (AEMWEs) offers cost advantages over proton-exchange membrane counterparts, mainly due to the good oxygen evolution reaction (OER) activity of platinum-group-metal-free catalysts in alkaline environments. However, the electrochemical oxidation of ionomers at the OER catalyst interface can decrease the local electrode pH, which limits AEMWE performance. Various strategies at the single-cell-level have been explored to address this issue. An international team of researchers (South Korea, USA – Los Alamos National Laboratory, University of North Carolina, Lawrence Berkeley National Laboratory) reviews the current understanding of electrochemical ionomer oxidation and strategies to […]
New study unveils 16,000 years of climate history in the tropical Andes
Phys.org August 12, 2024 Understanding tropical South America’s climate history can provide valuable insight into the water cycle, ecosystems, and future climate change, yet past temperature changes are not well-known. An international team of researchers (USA – Brown University, Florida Institute of Technology, the Netherlands) reconstructed temperature and rainfall since ~16,800 y ago in the tropical Andes Mountains. In addition to warming driven by rising atmospheric CO2 concentrations, they observed rapid temperature changes linked to changes in the deep ocean circulation. Their findings suggested that Amazonia’s ecosystems may be challenged by rapid temperature changes superposed on warming from sharply increasing […]
Researchers discover new material for optically-controlled magnetic memory
Phys.org August 9, 2024 The indirect exchange interaction between local magnetic moments via surface electrons has been long predicted to bolster the surface ferromagnetism in magnetic topological insulators (MTIs), which facilitates the quantum anomalous Hall effect. This unconventional effect is critical to determining the operating temperatures of future topotronic devices. However, the experimental confirmation of this mechanism has not been investigated in intrinsic MTIs. An international team of researchers (University of Chicago, University of Florida, Pennsylvania State University, Israel) combined time-resolved photoemission spectroscopy with time-resolved magneto-optical Kerr effect measurements to explain the unique electromagnetism at the surface of an intrinsic […]
Small but mighty: Why microbes could be part of climate solutions
Phys.org August 12, 2024 Methane and nitrous oxide (N2O) are greenhouse gases that rank second and third behind carbon dioxide as primary contributors to global warming and climate change. Outside of fossil sources, these gases are emitted by microorganisms as they interact with their environment. Researchers in Canada many strategies have targeted reduction of methane emissions. However, the microbial communities that live in these settings can respond to mitigation efforts by producing more N2O, which reduces or even negates the positive climate impact. Mitigation approaches often have not accounted for these trade-offs, and doing so requires additional monitoring to make […]
Study unveils limits on the extent to which quantum errors can be ‘undone’ in large systems
Phys.org August 11, 2024 Recently quantum error mitigation has been successfully applied to reduce noise in near-term applications. However, an international team of researchers (Germany, USA – Harvard University, France) identified strong limitations to the degree to which quantum noise can be effectively ‘undone’ for larger system sizes. They developed a framework which rigorously captures large classes of error-mitigation schemes in use today. By relating error mitigation to a statistical inference problem, they showed that even at shallow circuit depths comparable to those of current experiments, a superpolynomial number of samples was needed in the worst case to estimate the […]
Vertically stacked skin-like active-matrix display with ultrahigh aperture ratio
Phys.org August 6, 2024 Vertically stacked all-organic active-matrix organic light-emitting diodes are promising candidates for high-quality skin-like displays due to their high aperture ratio, extreme mechanical flexibility, and low-temperature processing ability. However, these displays suffer from process interferences when interconnecting functional layers made of all-organic materials. An international team of researchers (USA – Georgia Southern University, China) developed an integration strategy called “discrete preparation-multilayer lamination” based on microelectronic processes. They prepared each functional layer separately on different substrates to avoid chemical and physical damage caused by process interferences and introduced a single interconnect layer between each vertically stacked functional layer […]