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1. Atomic physics on a 50-nm scale: Realization of a bilayer system of dipolar atoms

   https://doi.org/10.1126/science.adh3023  

   Du, Li; Barral, Pierre; Cantara, Michael; de_Hond, Julius; Lu, Yu-Kun; Ketterle, Wolfgang (May 2024, Science)

   Controlling ultracold atoms with laser light has greatly advanced quantum science. The wavelength of light sets a typical length scale for most experiments to the order of 500 nanometers (nm) or greater. In this work, we implemented a super-resolution technique that localizes and arranges atoms on a sub–50-nm scale, without any fundamental limit in resolution. We demonstrate this technique by creating a bilayer of dysprosium atoms and observing dipolar interactions between two physically separated layers through interlayer sympathetic cooling and coupled collective excitations. At 50-nm distance, dipolar interactions are 1000 times stronger than at 500 nm. For two atoms in optical tweezers, this should enable purely magnetic dipolar gates with kilohertz speed. 

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2. Constraints on Nonthermal Pressure at Galaxy Cluster Outskirts from a Joint SPT and XMM-Newton Analysis

   https://doi.org/10.3847/2041-8213/adc676  

   Sarkar, Arnab; McDonald, Michael; Bleem, Lindsey; Bautz, Mark; Benson, Bradford A; Chakraborty, Priyanka; Grant, Catherine E; Jones, Christine; Kéruzoré, Florian; Miller, Eric D; et al (May 2025, The Astrophysical Journal Letters)

   Abstract We present joint South Pole Telescope and XMM-Newton observations of eight massive galaxy clusters (0.8–2 × 10¹⁵M_⊙) spanning a redshift range of 0.16–0.35. Employing a novel Sunyaev–Zel’dovich + X-ray fitting technique, we effectively constrain the thermodynamic properties of these clusters out to the virial radius. The resulting best-fit electron density, deprojected temperature, and deprojected pressure profiles are in good agreement with previous observations of massive clusters. For the majority of the cluster sample (five out of eight clusters), the entropy profiles exhibit a self-similar behavior near the virial radius. We further derive hydrostatic mass, gas mass, and gas fraction profiles for all clusters up to the virial radius. Comparing the enclosed gas fraction profiles with the universal gas fraction profile, we obtain nonthermal pressure fraction profiles for our cluster sample at  >0.5R₅₀₀, demonstrating a steeper increase betweenR₅₀₀andR₂₀₀that is consistent with the hydrodynamical simulations. Our analysis yields nonthermal pressure fraction ranges of 8%–28% (median: 15% ± 11%) atR₅₀₀and 21%–35% (median: 27% ± 12%) atR₂₀₀. Notably, weak-lensing mass measurements are available for only four clusters in our sample, and our recovered total cluster masses, after accounting for nonthermal pressure, are consistent with these measurements. 

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3. Advanced picosecond precision Radio Frequency Timer

   https://doi.org/10.1088/1748-0221/19/02/C02014  

   Zhamkochyan, S.; Kakoyan, V.; Abrahamyan, S.; Elbakyan, H.; Ayvazyan, G.; Ayvazyan, R.; Ghalumyan, A.; Kakoyan, A.; Mayilyan, S.; Papyan, A.; et al (February 2024, Journal of Instrumentation)

   Abstract A new type of radio frequency (RF) timing technique is presented. It is based on a helical deflector, which performs circular or elliptical sweeps of photo- or secondary electrons, accelerated to keV energies, by means of RF fields in the 500–1000 MHz range. By converting a time distribution of the electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing, similar to streak cameras. Detection of the scanned electrons, using a position sensitive detector based on microchannel plates and a delay line anode, resulted in a timing resolution of 10 ps, which can be potentially improved to 1 ps. RF-Timer-based single photon and heavy ion detectors have potential applications in different fields of science and industry, which include high energy nuclear physics and imaging technologies. This technique could play a crucial role in developing of sub 10 ps Time-of-Flight Positron Emission Tomography. 

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4. Laser additive manufacturing of powdered bismuth telluride

   https://doi.org/10.1557/jmr.2018.390  

   Zhang, Haidong; Hobbis, Dean; Nolas, George S.; LeBlanc, Saniya (December 2018, Journal of Materials Research)

   Traditional manufacturing methods restrict the expansion of thermoelectric technology. Here, we demonstrate a new manufacturing approach for thermoelectric materials. Selective laser melting, an additive manufacturing technique, is performed on loose thermoelectric powders for the first time. Layer-by-layer construction is realized with bismuth telluride, Bi 2 Te 3 , and an 88% relative density was achieved. Scanning electron microscopy results suggest good fusion between each layer although multiple pores exist within the melted region. X-ray diffraction results confirm that the Bi 2 Te 3 crystal structure is preserved after laser melting. Temperature-dependent absolute Seebeck coefficient, electrical conductivity, specific heat, thermal diffusivity, thermal conductivity, and dimensionless thermoelectric figure of merit ZT are characterized up to 500 °C, and the bulk thermoelectric material produced by this technique has comparable thermoelectric and electrical properties to those fabricated from traditional methods. The method shown here may be applicable to other thermoelectric materials and offers a novel manufacturing approach for thermoelectric devices. 

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5. Probing Local Emission Properties in InGaN/GaN Quantum Wells by Scanning Tunneling Luminescence Microscopy

   https://doi.org/10.1002/pssb.202200365  

   Sauty, Mylène; Alyabyeva, Natalia; Lynsky, Cheyenne; Chow, Yi Chao; Nakamura, Shuji; Speck, James S.; Lassailly, Yves; Rowe, Alistair C. H.; Weisbuch, Claude; Peretti, Jacques (November 2022, physica status solidi (b))

   Scanning tunneling electroluminescence (STL) microscopy is performed on a 3 nm‐thick InGaN/GaN quantum well (QW) with [In] = 0.23 such that the main light emission occurs in the green. The technique is used to map the radiative recombination properties at a scale of a few nanometers and correlate the local electroluminescence map with the surface topography simultaneously imaged by scanning tunneling microscopy. While the expected green emission is observed all over the sample, measurements performed on a 500 nm × 500 nm area around a 150 nm‐large and 2.5 nm‐deep hexagonal defect reveal intense emission peaks at higher energies close to the defect edges, features which are not visible in the macrophotoluminescence spectrum of the sample. Via a fitting of the local tunneling electroluminescence spectra, quantitative information on the fluctuations of the intensity, peak energy, width, and phonon replica intensity of the different spectral contributions is obtained, which provides information on carrier localization in the QW. This procedure also indicates that the carrier diffusion length on the probed area of the QW is shorter than 50 nm. 

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