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1. Foundry-fabricated photonic integrated circuit for flex-grid entanglement distribution

   https://doi.org/10.1364/CLEO_AT.2024.JW2A.139  

   Miloshevsky, Alexander; Lu, Hsuan-Hao; Cohen, Lucas M; Myilswamy, Karthik V; Fatema, Saleha; Alshowkan, Muneer; Weiner, Andrew M; Lukens, Joseph M (January 2024, Optica Publishing Group)

   We demonstrate a silicon photonic integrated circuit fabricated through the CMOS manufacturing process, which features a bidirectionally pumped microring to achieve over 116 high-fidelity polarization entangled channels covering the entire optical C+L-band for flex-grid entanglement distribution. 

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2. Recent developments in tornado theory and observations

   https://doi.org/10.1088/1361-6633/ad7f6a  

   Rotunno, Richard; Bluestein, Howard B (October 2024, Reports on Progress in Physics)

   Abstract This article critically reviews research on tornado theory and observations over the last decade. From the theoretical standpoint, the major advances have come through improved numerical-simulation models of supercell convective storms, which contain the tornado’s parent circulation. These simulations are carried out on a large domain (to capture the supercell’s circulation system), but with high grid resolution and improved representations of sub-grid physics (to capture the tornado). These simulations offer new insights into how and why tornadoes form in some supercells, but not others. Observational advances have come through technological improvements of mobile Doppler radars capable of rapid scanning and dual-polarization measurements, which offer a much more accurate view of tornado formation, tornado structure, and the tornado’s place within its parent supercell. 

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3. Loaded Microstrip Network Transmision-Line Metamaterials on an Irregular Grid

   https://doi.org/10.1109/AP-S/USNC-URSI47032.2022.9886547  

   Maurer, Tina E.; Kwon, Do-Hoon (July 2022, 2022 IEEE International Symposium on Antennas and Propagation)

   A planar loaded microstrip network metamaterial on an irregular grid for modeling 2-D electromagnetic environment in TE polarization is presented. The technique is applied to a Luneburg lens example toward printed circuit implementation and verification. 

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4. Multiple Metamaterial Pattern Integration for Polarization Selective Photodetector Applications

   https://doi.org/10.1557/adv.2018.43  

   Shemelya, Corey; Pfiester, Nicole A.; DeMeo, Dante; Rotter, Thomas; Balakrishnan, Ganesh; Vandervelde, Thomas E. (January 2018, MRS Advances)

   ABSTRACT Interest in active metamaterial (MM) devices has recently increased due to their potential for tunable, switchable, and scalable optical responses. More specifically, a dynamic, on-chip MM polarizer has applications ranging from material characterization to sensing without the need for cumbersome external filters. This work demonstrates efforts to optimize MM devices for dynamic polarization filtering by combining elements from split-ring resonators, wire-pairs, and fishnet patterns. The polarization grid has been designed to operate under an applied voltage with simulated on/off ratios of 75% and dynamic polarization selectivity of 70%. Samples have been fabricated using epitaxial GaAs on sapphire with various n-type doping concentrations to approximate electrical tuning. 

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5. Supermassive Black Hole Spin Constraints from Polarimetry in an Equatorial Disk Model

   https://doi.org/10.3847/2041-8213/ad9bb4  

   Palumbo, Daniel_C M (December 2024, The Astrophysical Journal Letters)

   Abstract The Event Horizon Telescope has released polarized images of the supermassive black holes Messier 87* (M87*) and Sagittarius A* accretion disks. As more images are produced, our understanding of the average polarized emission from near the event horizon improves. In this Letter, we use a semianalytic model for optically thin, equatorial emission near a Kerr black hole to study how spin constraints follow from measurements of the average polarization spiral pitch angle. We focus on the case of M87* and explore how the direct, weakly lensed image spiral is coupled to the strongly lensed indirect image spiral, and how a precise measurement of both provides a powerful spin tracer. We find a generic result that the spin twists the direct and indirect image polarization in opposite directions. Using a grid search over model parameters, we find a strong dependence of the resulting spin constraint on plasma properties near the horizon. Grid constraints suggest that, under reasonable assumptions for the accretion disk, a measurement of the direct and indirect image spiral pitch angles to ±5° yields a dimensionless spin amplitude measurement with uncertainty ${\sigma }_{\mid a_{*}\mid }\sim 0.25$for radially infalling models but otherwise provides only weak constraints; an error of 1^∘can reach ${\sigma }_{\mid a_{*}\mid }\sim 0.15$. We also find that a well-constrained rotation measure greatly improves spin measurements. Assuming that equatorial velocity and magnetic field are oppositely oriented, we find that the observed M87* polarization pattern favors models with strong radial velocity components, which are close to optimal for future spin measurements. 

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