Phys.org October 28, 2024 Unidirectional imagers form images of input objects only in one direction. Researchers at UCLA reported unidirectional imaging under spatially partially coherent light and demonstrated high-quality imaging only in the forward direction (A → B) with high power efficiency while distorting the image formation in the backward direction (B → A) along with low power efficiency. Their analyses revealed that when illuminated by a partially coherent beam with a correlation length of ≥∼1.5λ, where λ was the wavelength of light, diffractive unidirectional imagers achieved robust performance, exhibiting asymmetric imaging performance between the forward and backward directions. A […]
Tag Archives: S&T USA
The corners where atoms meet may provide a path to new materials for extreme conditions
Phys.org October 16, 2024 A team of researchers in the US (George Washington University, George Mason University, Lawrence Berkeley University, Johns Hopkinson University, Sandia National Laboratory, Leigh University) presented large-scale atomistic simulations that revealed triple junction (TJ) segregation in Pt–Au nanocrystalline alloys in agreement with experimental observations. While existing studies suggested grain boundary solute segregation as a route to thermally stabilize nanocrystalline materials with respect to grain coarsening, the researchers quantitatively showed that it was specifically the segregation to TJs that dominated the observed stability of the alloys. The results showed that doping the TJs made them immobile, thereby locking […]
Researchers reveal quantum advantage that could advance future sensing devices
Phys.org October 16, 2024 Quantum metrology takes advantage of quantum correlations to enhance the sensitivity of sensors and measurement techniques beyond their fundamental classical limit. The use of both temporal and spatial correlations present in quantum states of light can extend quantum-enhanced sensing to a parallel configuration that can simultaneously probe an array of sensors or independently measure multiple parameters. Researchers at the University of Oklahoma used multispatial-mode bright twin beams of light to probe a four-sensor quadrant plasmonic array. They showed that it is possible to independently and simultaneously measure local changes in refractive index for all four sensors […]
Analysis of approximately 75 million publications finds those employing AI are more likely to be a ‘hit paper’
Phys.org October 11, 2024 Despite enormous efforts devoted to understanding AI’s economic impacts, we lack a systematic understanding of the benefits to scientific research associated with the use of AI. Researchers at the Northwestern University developed a measurement framework found that the use and benefits of AI appeared widespread throughout the sciences, growing especially rapidly since 2015. However, there is a substantial gap between AI education and its application in research, highlighting a misalignment between AI expertise supply and demand. Their analysis revealed demographic disparities, with disciplines with higher proportions of women or Black scientists reaping fewer benefits from AI, […]
Atmospheric rivers are shifting poleward, reshaping global weather patterns
Phys.org October 14, 2024 Atmospheric rivers (ARs) are key agents in distributing extratropical precipitation and transporting moisture poleward. Climate models suggest an increase in AR activity in the extratropics over the past four decades. However, analyses indicate a poleward shift of ARs during boreal winter in both hemispheres. Researchers at UC Santa Barbara demonstrated that low-frequency sea surface temperature variability in the tropical eastern Pacific exhibited a cooling tendency since 2000 that played a key role in driving global AR shift, mostly over extratropical oceans. This mechanism also operated on interannual timescales, controlled by the El Niño–Southern Oscillation, and was […]
Engineering perovskite materials at the atomic level paves way for new lasers, LEDs
Phys.org October 11, 2024 Layered hybrid perovskites (LHPs) have emerged as promising reduced-dimensional semiconductors for next-generation photonic and energy applications where controlling the size, orientation, and distribution of quantum wells (QWs) is of paramount importance. A team of researchers in the US (North Carolina State University, Brookhaven National Laboratory) revealed that bulky molecular spacers act as crystal-terminating ligands to form colloidal nanoplatelets (NPLs) during early stages of LHP formation. They proved that NPLs ripen and grow, playing a decisive role in the time evolution of QW size, population distribution, and orientation. They demonstrated that antisolvent drip interrupts NPL ripening and […]
New light-induced material shows powerful potential for quantum applications
Phys.org October 15, 2024 By using semiconducting hybrid perovskite as an exploratory platform, a team of researchers in the US (Northern Illinois University, Argonne National Laboratory) discovered that Nd2+ doped CH3NH3PbI3 (MAPbI3) perovskite exhibited a Kondo-like exciton-spin interaction under cryogenic and photoexcitation conditions. From a mechanistic standpoint, such extended charge separation states are the consequence of the trap state enabled by the antiferromagnetic exchange interaction between the light-induced exciton and the localized 4 f spins of the Nd2+ in the proximity. Importantly, this Kondo-like exciton-spin interaction can be modulated leading to exciton recombination at the dynamics comparable to pristine MAPbI3… read […]
Solar-powered desalination system requires no extra batteries
MIT News October 8, 2024 In the developing world, where there are unreliable energy sources of water, they rely increasingly on saline groundwater. Traditional renewable desalination technologies require sizable energy storage for sufficient water production, leading to increased cost, maintenance and complexity. An international team of researchers (USA – MIT, UK, Germany) demonstrated a simple control strategy using photovoltaic electrodialysis (PV-ED) to enable direct-drive optimally controlled desalination at high production rates. This control scheme was implemented on a fully autonomous, community-scale PV-ED prototype system and operated for 6 months in New Mexico on real brackish groundwater. The prototype fully harnessed 94% […]
Bioengineered microorganisms offer new tool for plastic waste breakdown
Phys.org October 7, 2024 Mussels exploit the exceptional adhesive properties of 3,4-Dihydroxy-L-phenylalanine (DOPA) to adhere to a wide range of surfaces. Through the optimization of the DOPA incorporation system researchers at Rice University demonstrated significantly improved binding abilities to various organic and metallic materials. DOPA incorporation system was also applied to engineer adhesive bacteria which increased their binding capability to diverse materials including 400 folds of improvement to polyethylene terephthalate (PET). Enhancement in PET binding allowed a unique approach for PET degradation and Genetic Code Expansion in cell engineering… read more. TECHNICAL ARTICLE
Atoms on the edge
MIT News September 6, 2024 The chiral edge modes lie at the heart of the integer and fractional quantum Hall effects, and their robustness against noise and disorder reflects the quantization of Hall conductivity in these systems. Despite their importance, the controllable injection of edge modes, and direct imaging of their propagation, structure and dynamics, remains challenging. Researchers at MIT demonstrated the distillation of chiral edge modes in a rapidly rotating bosonic superfluid confined by an optical boundary. By tuning the wall sharpness they revealed the smooth crossover between soft wall behaviour in which the propagation speed was proportional to […]