Materials research explores design rules and synthesis of quantum memory candidates

Phys.org   March 11, 2024 Stoichiometric Eu3+ compounds have recently shown promise for building dense, optically addressable quantum memory as the cations’ long nuclear spin coherence times and shielded 4f electron optical transitions provide reliable memory platforms but finding rare linewidth behavior within a wide range of potential chemical spaces remains difficult. Researchers at the University of Illinois, Urbana─Champaign, have found density functional theory (DFT) procedures that reliably reproduce known phase diagrams and correctly predict two experimentally realized quantum memory candidates. They synthesized the double perovskite halide Cs2NaEuF6 which is an air-stable compound with a calculated band gap of 5.0 eV […]

New research on tungsten unlocks potential for improving fusion materials

Phys.org   March 13, 2024 Understanding phonon scattering has remained challenging and requires detailed information on interactions between phonons and electrons. An international team of researchers (USA – SLAC National Accelerator Laboratory, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Sweden, Italy) used an ultrafast electron diffuse scattering technique to resolve the nonequilibrium phonon dynamics in femtosecond–laser-excited tungsten in both time and momentum. They determined transient populations of phonon modes which show strong momentum dependence initiated by electron-phonon coupling. For phonons near Brillouin zone border, they observed a transient rise in their population on a timescale driven by the strong electron-phonon […]

New type of tunable filter reveals the potential for terahertz wireless communications

Phys.org   March 11, 2024 Researchers in Japan constructed a tunable Fabry–Perot interferometer (FPI) by controlling the effective refractive index of pitch-variable subwavelength gratings (PV-SWGs) that were incorporated into an FP cavity. The period of the PV-SWG could be varied to change the effective refractive index and shift the optical resonant frequency of the FPI. Compared with conventional methods that tune the optical resonance by adding fillers or deforming the cavity, the  FPI obtained a higher transmission and quality factor (Q-factor) for the transmittance peak, and its resonant frequency could be shifted by simply stretching the PV-SWG. According to the researchers […]

Novel method for controlling light polarization uses liquid crystals to create holograms

Phys.org  March 11, 2024 Metasurfaces are candidates for vectorial optics polarization, but their static post-fabrication geometry largely limits dynamic tunability. Liquid crystal (LC) is usually employed as an additional index-changing layer together with metasurfaces. However, most of the reported LCs only impart a varying but uniform phase on top of that from the metasurface. An international team of researchers (China, Singapore) pixelated a single-layer LC to display versatile and tunable vectorial holography, in which the polarization and amplitude could be arbitrarily and independently controlled at varying spatial positions. The subtle and vectorial LC-holography highlighted the broadband and electrically switchable functionalities. […]

Novel method improves Fourier transform infrared spectroscopy detection of ultra-low concentration trace substances

Phys.org  March 7, 2024 High-resolution solar spectra play a crucial role in research pertaining to atmospheric vertical profiles and analysis of atmospheric composition. However, the improvement of spectral resolution is subject to certain limitations due to hardware constraints. Researchers in China proposed multi-step linear prediction (MSLP) method based on sliding windows to enhance the spectral resolution of passive remote sensing FTIR spectra, thereby improving the accuracy and reliability of atmospheric composition analysis. Their method improved the spectral resolution of passive remote sensing FTIR spectra. In simulations, the MSLP method significantly enhanced the spectral resolution of passive remote sensing FTIR spectra. […]

Paper AI sensor mimics brain for health monitoring

Nanowerk  March 11, 2024 Physical reservoir computing (PRC), which mimics the human brain using physical phenomena, offers a low-power consumption architecture. However, creating a flexible and easily disposable sensors using PRC capable of processing optical signals with sub-second response times suitable for biological signals presents a challenge. Researchers in Japan designed disposable and flexible paper-based optoelectronic synaptic devices which are composed of nanocellulose and ZnO nanoparticles, for PRC. The device exhibited synaptic photocurrent in response to optical input.  The memory capacity of short-term memory task, indicating the device’s ability to store past information was 1.8. It could recognize handwritten digits […]

Powerless mechanoluminescent touchscreen underwater

EurekAlert  March 6, 2024 Optical properties of afterglow luminescent particles (ALPs) in mechanoluminescence (ML) and mechanical quenching (MQ) have diverse technological applications. An international team of researchers (South Korea, USA – Stanford University) designed ALPs for the development of a wearable and rewritable photonic display system as a communication toolbox under dark conditions or underwater environments with limited communication. The system demonstrated long-lasting MQ after short ML along the handwritten trajectories with mechanical pressure and the written content could be easily erased by short UV light irradiation, preserving the system integrity with the high reproducibility of ML and MQ responses. […]

Preventing magnet meltdowns before they can start

Science Daily  March 11, 2024 Unlike conventional magnets where a normal zone expands typically quickly, and the stored energy is dissipated across a large volume of the windings, a normal zone in a High-temperature superconductor (HTS) magnet propagates slowly and, thus, can heat up quickly to high temperatures destroying the conductor. At the same time, growing experimental evidence suggests that HTS conductors can operate in a stable dissipative flux flow regime for a substantial range of operational currents before entering an irreversible thermal runaway. Researchers at Lawrence Berkeley National Laboratory proposed a simple criterion for the thermal runaway in HTS […]

Researchers achieve quantum key distribution for cybersecurity in novel experiment

Phys.org   March 13, 2024 In their conference paper researchers at Oak Ridge National Laboratory reported on the first implementation of their CV-QKD scheme over a deployed optical fiber network. According to the researchers, in continuous variable quantum key distribution (CV-QKD), using a truly local (not transmitted over the network) oscillator improves security… read more. TECHNICAL ARTICLE 

Researchers find exception to 200-year-old scientific law governing heat transfer

Phys.org  March 4, 2024 Researchers at UMass, Amherst, revisited the Fourier’s law for heat transfer and transport within translucent materials. They compared the model predictions to infrared-based measurements with nearly mK temperature resolution. After heat pulses, they found macroscale non-Gaussian tails in the surface temperature profile. At steady state, they found  macroscale anomalous hot spots when the sample was topographically rough. These discrepancies from Fourier’s law for translucent materials suggested that internal radiation whose mean-free-path is millimeters interacted with defects to produce small heat sources that by secondary emission afford an additional, non-local mode of heat transport. According to the […]