Phys.org July 19, 2021 The spin color centers in silicon carbide, including silicon vacancies and divacancies have excellent optical and spin properties. Researchers in China have presented the coherent manipulation of single divacancy spins in 4H-SiC with a high readout contrast (−30%) and a high photon count rate under ambient conditions, which are competitive with the nitrogen-vacancy centres in diamond. Coupling between a single defect spin and a nearby nuclear spin is also observed. They provided a theoretical explanation for the high readout contrast by analysing the defect levels and decay paths. Since the high readout contrast is important in […]
Tag Archives: S&T China
New ‘Metafabric’ Passively Cools The Human Body by Almost 5 Degrees Celsius
Science Alert July 13, 2021 The metafabric developed by researchers in China uses titanium oxide-polylactic acid composite nanoparticles laminated with a thin layer of polytetrafluoroethylene (PTFE). It is designed to strongly reflect visible light (VIS), mid-infrared (MIR) and ultraviolet (UV) ranges. The wide distribution of nanoparticles, when combined with PTFE nanobeads, provides broad-spectrum scattering and reflectivity across the UV-VIS-NIR band. They tested the material in clear sky conditions measuring the temperature of the fabric in comparison to other common materials lying on a panel. Under peak solar irradiance between 11:00 and 15:00, the temperature of the metafabric was approximately 5.0°, […]
Has the stilling of surface wind speed ended in China?
Phys.org June 28, 2021 Since the 1960s, the global land surface wind speed (SWS) has significantly weakened, a phenomenon known as global terrestrial stilling. The stilling reversed around 2010 and global SWS is strengthening. It has seriously affected the ecological environment and social economy, especially restricting the sustainable development of the wind energy industry. Researchers in China analyzed the transition and regional differences in the long-term trends of the SWS in China based on observational SWS data from 1971 to 2019. The results showed that annual mean SWS in China underwent a reversal from a continuous weakening trend to a […]
Researchers discover unusual competition between charge density wave and superconductivity
Phys.org July 5, 2021 To study the layered cage structure superconductor CsV3Sb5, which has a charge density wave (CDW) transition temperature of 94 K, researchers in China conducted high-pressure electrical transport and magnetic susceptibility measurements. They found that the CDW transition is monotonically suppressed by pressure, and superconductivity is enhanced with increasing pressure up to P1 ≈ 0.7 GPa. They found an unexpected suppression of superconductivity until pressure around 1.1 GPa, after that, Tc was enhanced with increasing pressure again. The CDW was completely suppressed at a critical pressure P2 ≈ 2 GPa together with a maximum Tc of about 8 K. The pressure-dependent Tc showed an unexpected […]
Non-stop signal achieved in high-power Erbium-doped mid-infrared lasers
Phys.org July 1, 2021 Based on their previous research work on laser, researchers in China further improved the laser performance of Er:YAP laser crystal by laser-diode side-pumping method. A Er:YAP crystal rod with concave end-faces was used to compensate the thermal lensing effect. They achieved maximum output power of 26.75 W at 250 Hz, and 13.18 W at 1000 Hz. They demonstrated a LD side-pumped and electro-optical Q-switched Er,Pr:YAP laser with emission at 2.7 μm. A giant pulse laser was obtained with pulse energy of 20.5 mJ, pulse width of 61.4 ns, and peak power of 0.33 MW at the […]
Optical superoscillation without side waves
EurekAlert June 24, 2021 Optical superoscillation refers to a phenomenon of a wave packet that can oscillate locally faster than its highest Fourier component, which potentially produces an extremely localized wave in the far field. It provides an alternative way to overcome the diffraction limit and improve the resolution of an optical microscopy system. However, the optical superoscillatory waves are inevitably accompanied by strong side lobes, which limits their fields of view and, hence, potential applications. Researchers in China report both experimentally and theoretically a new superoscillatory wave form, which not only produces significant feature size down to deep subwavelength, […]
The first observation of the superscattering effect of metamaterials
Phys.org June 23, 2021 Superscattering effects, such as stopping wave propagation in an air channel, have not been verified from illusion devices physically because of the challenge of metamaterial design, fabrication, and material loss. Researchers in China have implemented a big metamaterial superscatterer, and experimentally demonstrated its superscattering effect at microwave frequencies by field-mapping technology. They confirmed that superscattering is originated from the excitation of surface plasmons. They experimentally showed that an invisible gateway integrated with superscatterer could stop electromagnetic waves in an air channel with a width much larger than the cutoff width of the corresponding rectangular waveguide. The […]
DNA circuits
EurekAlert June 2, 2021 Researchers in China have developed a configurable, multi-mode logic switching network that reacts differently with its surroundings depending on pH and DNA input. They developed a series of four DNA switches, each with slightly different lengths and combinations of bases. At a slightly alkaline pH of 8, two of the switches formed triple-stranded DNA, while the others remained loosely stretched out. These reactions and folds led to secondary reactions, which were utilized by the researchers as logic functions in the switching circuit. In demonstration DNA acted as a crosslinker, joining the polymer molecules in the gel […]
Researchers realize coherent storage of light over one hour
Phys.org May 10, 2021 One solution for remote quantum communication lies in quantum memories: photons are stored in long-lived quantum memory (quantum flash drive) and then quantum information is transmitted by the transportation of the quantum memory. Researchers in China adopted the spin wave atomic frequency comb (AFC) protocol in a ZEFOZ field (ZEFOZ-AFC) method to implement long-lived storage of light signals. They used dynamical decoupling to protect spin coherence and extend storage time. They demonstrated coherent storage of light in an atomic frequency comb memory over 1 hour with a fidelity of 96.4%. The study meets the basic requirements […]
An uncrackable combination of invisible ink and artificial intelligence
Phys.org May 5, 2021 Even as electronic records advance, paper is still a common way to preserve data. Researchers in China have developed a paper information protection scheme by combining fluorescent invisible ink and artificial intelligence. The ink was prepared by dissolving carbon nanoparticles in water, which has a high quantum yield and outstanding light stability and salt stability, thus ensures the integrity of information in complex environments. A neural network was specially trained based on ultraviolet light excited symbols printed by invisible ink. Using this scheme, the correct information could only be read with the specially trained neural network […]