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1. Integrated visible-light polarization rotators and splitters for atomic quantum systems

   https://doi.org/10.1364/OL.509747  

   Hattori, Ashton; Sneh, Tal; Notaros, Milica; Corsetti, Sabrina; Callahan, Patrick_T; Kharas, Dave; Mahony, Thomas; McConnell, Robert; Chiaverini, John; Notaros, Jelena (March 2024, Optics Letters)

   In this work, we design and experimentally demonstrate the first, to the best of our knowledge, integrated polarization splitters and rotators at blue wavelengths. We develop compact and efficient designs for both a polarization splitter and rotator at a 422-nm wavelength, an important laser-cooling transition for⁸⁸Sr⁺ions. These devices are fabricated in a 200-mm wafer-scale process and experimentally demonstrated, resulting in a measured polarization-splitter transverse-electric thru-port coupling of 98.0% and transverse-magnetic tap-port coupling of 77.6% for a compact 16-µm-long device and a polarization-rotator conversion efficiency of 92.2% for a separate compact 111-µm-long device. This work paves the way for more sophisticated integrated control of trapped-ion and neutral-atom quantum systems. 

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2. Changes in electrical generator cooling systems: Are they cost‐effective sources of water now and under climate change?

   https://doi.org/10.1111/1752-1688.13111  

   Yang, Yingqian; Fei, Chengcheng J.; McCarl, Bruce A. (February 2023, JAWRA Journal of the American Water Resources Association)

   Abstract In the United States, thermal power plant electrical generators (EGs) are large water diverters and consumptive users who need water for cooling. Retrofitting existing cooling systems to dry cooling and building new facilities with dry cooling can save water and reduce EG's vulnerability to drought. However, this can be an expensive source of water. We estimate that the cost of water saved by retrofitting cooling in existing EGs ranges from $0.04/m³to $18/m³depending on facility characteristics. Also water savings from building new EGs with dry cooling ranges in cost per unit water from $1.29/m³to $2.24/m³. We compare costs with that for water development projects identified in the Texas State Water Plan. We find the water cost from converting to dry cooling is lower than many of the water development possibilities. We then estimate the impact of climate change on the cost of water saved, finding climate change can increase EG water use by up to 9.3% and lower the costs of water saved. Generally, it appears that water planners might consider cooling alterations as a cost competitive water development alternative whose cost would be further decreased by climate change. 

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3. Strengthening Aqueous Electrolytes without Strengthening Water

   https://doi.org/10.1002/anie.202307212  

   Tang, Longteng; Xu, Yunkai; Zhang, Weiyi; Sui, Yiming; Scida, Alexis; Tachibana, Sean R.; Garaga, Mounesha; Sandstrom, Sean K.; Chiu, Nan‐Chieh; Stylianou, Kyriakos C.; et al (July 2023, Angewandte Chemie International Edition)

   Abstract Aqueous electrolytes typically suffer from poor electrochemical stability; however, eutectic aqueous solutions—25 wt.% LiCl and 62 wt.% H₃PO₄—cooled to −78 °C exhibit a significantly widened stability window. Integrated experimental and simulation results reveal that, upon cooling, Li⁺ions become less hydrated and pair up with Cl⁻, ice‐like water clusters form, and H⋅⋅⋅Cl⁻bonding strengthens. Surprisingly, this low‐temperature solvation structure does not strengthen water molecules’ O−H bond, bucking the conventional wisdom that increasing water's stability requires stiffening the O−H covalent bond. We propose a more general mechanism for water's low temperature inertness in the electrolyte: less favorable solvation of OH⁻and H⁺, the byproducts of hydrogen and oxygen evolution reactions. To showcase this stability, we demonstrate an aqueous Li‐ion battery using LiMn₂O₄cathode and CuSe anode with a high energy density of 109 Wh/kg. These results highlight the potential of aqueous batteries for polar and extraterrestrial missions. 

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4. Laser cooling with adiabatic transfer on a Raman transition

   https://doi.org/10.1088/1367-2630/ab2f3c  

   Greve, G. P.; Wu, B.; Thompson, J. K. (July 2019, New Journal of Physics)

   Abstract Sawtooth Wave Adiabatic Passage (SWAP) laser cooling was recently demonstrated using a narrow-linewidth single-photon optical transition in atomic strontium and may prove useful for cooling other atoms and molecules. However, many atoms and molecules lack the appropriate narrow optical transition. Here we use such an atom,⁸⁷Rb, to demonstrate that two-photon Raman transitions with arbitrarily-tunable linewidths can be used to achieve 1D SWAP cooling without significantly populating the intermediate excited state. Unlike SWAP cooling on a narrow transition, Raman SWAP cooling allows for a final 1D temperature well below the Doppler cooling limit (here, 25 times lower); and the effective excited state decay rate can be modified in time, presenting another degree of freedom during the cooling process. We also develop a generic model for Raman Landau–Zener transitions in the presence of small residual free-space scattering for future applications of SWAP cooling in other atoms or molecules. 

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5. Albedo of crops as a nature-based climate solution to global warming

   https://doi.org/10.1088/1748-9326/ad5fa2  

   Lei, Cheyenne; Chen, Jiquan; Ibáñez, Inés; Sciusco, Pietro; Shirkey, Gabriela; Lei, Ming; Reich, Peter; Robertson, G_Philip (July 2024, Environmental Research Letters)

   Abstract Surface albedo can affect the energy budget and subsequently cause localized warming or cooling of the climate. When we convert a substantial portion of lands to agriculture, land surface properties are consequently altered, including albedo. Through crop selection and management, one can increase crop albedo to obtain higher levels of localized cooling effects to mitigate global warming. Still, there is little understanding about how distinctive features of a cropping system may be responsible for elevated albedo and consequently for the cooling potential of cultivated lands. To address this pressing issue, we conducted seasonal measurements of surface reflectivity during five growing seasons on annual crops of corn-soybean–winter wheat (Zea mays L.- Glycine max L.Merrill—Triticum aestivum L.; CSW) rotations at three agronomic intensities, a monoculture of perennial switchgrass, and perennial polycultures of early successional and restored prairie grasslands. We found that crop-species, agronomic intensity, seasonality, and plant phenology had significant effects on albedo. The mean ± SD of albedo was highest in perennial crops of switchgrass (Panicum virgatum; 0.179 ± 0.04), intermediate in early successional crops (0.170 ± 0.04), and lowest in a reduced input corn systems with cover crops (0.154 ± 0.02). Thestrongest cooling potentials were found in soybean (−0.450 kg CO₂e m⁻²yr⁻¹) and switchgrass (−0.367 kg CO₂e m⁻²yr⁻¹), with up to −0.265 kg CO₂e m⁻²yr⁻¹of localized climate cooling annually provided by different agroecosystems. We also demonstrated how diverse ecosystems, leaf canopy, and agronomic practices can affect surface reflectivity and provide another potential nature-based solution for reducing global warming at localized scales. 

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