Phys.org February 25, 2022 China National Space Agency (CNSA) released its 10-year plan on January 28. Some main focal points include improving the sustainability of their rocket launches, improving global position system, partnering with Russia on lunar exploration, maintaining and expanding the Tiangong space station, researching the underlying technology for a Mars sample return mission, and building a global partnership to build a research station on the moon. Launching above the atmosphere is key to any global positioning system, which they plan to improve dramatically in the next five years. With some help from Russia, CNSA hopes to complete another […]
Tag Archives: S&T China
Researchers use solar cells to achieve fast underwater wireless communication
Science Daily February 16, 2022 The greatest problem in using solar panels for underwater wireless optical communication (UWOC) systems is the limited bandwidth of the solar panel, which was originally optimized for energy harvesting rather than communication. Researchers in China studied the fundamentals of the solar array and proposed series-connected solar arrays for high-speed underwater detection. As they increased the size of the solar array from 1×1 to 3×3, the −20-dB bandwidth increased from 4.7 MHz to 24.2 MHz. To further improve the frequency response, they applied a reverse bias on the array. With a reverse bias voltage of 90 […]
Chinese and U.S. University Rankings
Center for Security and Emerging Technology January 28, 2022 In a CSET Report researchers at Georgetown University assess the quality of universities in China and the United States based on their performance in two well-regarded rankings of global universities. They found Chinese universities have steadily moved up the rankings over time, driven largely by increases in research productivity and a series of state-sponsored higher education initiatives. Between 2010 and 2020, the number of U.S. universities that appeared in the top 500 on at least one global ranking dropped from 160 to 137, while the number that appeared on both rankings […]
Researchers find new way of gaining quantum control from loss
Phys.org January 24, 2022 Researchers in China implemented dissipative spin–orbit-coupled bands filled with ultracold fermions and observed parity-time symmetry breaking as a result of the competition between the spin–orbit coupling and dissipation. Tunable dissipation, introduced by state-selective atom loss, enabled them to tune the energy gap and close it at the critical dissipation value, the so-called exceptional point. Near the critical point, the state evolution exhibited a chiral response, which enabled them to tune the spin–orbit coupling and dissipation dynamically, revealing topologically robust chiral spin transfer when the quantum state encircled the exceptional point. According to the researchers this demonstrates […]
New p-type, near-infrared transparent conducting thin films with better performance
Phys.org January 19, 2022 The low conductivity of previous CuMO2 films obstructs the development of delafossite-based electronics. Researchers in China designed and fabricated a new p-type 4d transition metal Rh-based CuRhO2 film by a facile solution method. It has room-temperature conductivity as high as 735 S cm−1 which was achieved by substituting 10%Mg in Rh sites. The acceptor-doped CuRhO2 films exhibited high near-infrared transmittance of 85–60% with low room-temperature sheet resistance of 4.28–0.18 kΩ sq−1. The electronic structure, electrical transport mechanism, and intra-band excitation feature for the CuRhO2 film are unveiled. According to the researchers theoretical and experimental results contribute […]
Scientists invent lead-free composite shielding material for neutrons and gamma-rays
Phys.org December 23, 2021 Through a series of intricate and comprehensive experiments researchers in China tested and certified the composite, modified-gadolinium oxide/boron carbide/high density polyethylene (Gd2O3/B4C/HDPE) as safe and effective to shield neutron and gamma rays. Fast neutrons collide with gadolinium (Gd) inelastically and collide elastically with hydrogen until they become thermal neutrons, finally, absorbed by high Z element Gd and boron. The experimental results show that the neutron shielding rate of the composite can reach 98% under the condition of 15 cm thickness in CF-252 environment. In cS-137 and CO-60 environments, the gamma shielding rates of the composite are […]
‘Anti-aging’ chemistry taken from nature overcomes next-gen lithium battery decay
Phys.org November 15, 2021 Degradation occurs pretty much everywhere in nature since oxygen is one of the elements most capable of attracting electrons from other atoms and molecules. Organisms often produce different types of enzymes that work to scavenge active oxygen and free radicals to alleviate the issue. Inspired by the anti-oxygen coping mechanisms in nature researchers in China developed a photostabilizer—a simple, anti-aging binder additive to the electrolyte that can scavenge the singlet oxygen atoms and free radicals as they occur. Through experimental investigation and theoretical calculation, they found that the scavenging mechanism in layered transition metal oxides-based lithium […]
New phonon-based and magneto-tunable monochromatic terahertz source
Phys.org November 10, 2021 Researchers in China developed a highly efficient magneto-tunable and phonon-based monochromatic THz generator with a frequency of ~0.9 THz using a 2D ferromagnetic Cr2Ge2Te6 crystal. They combined theoretical and experimental approaches and innovatively exploited the excellent properties of its van der Waals interlayered breathing phonon mode (boson) with THz-TDS (time domain spectroscopy) magneto-optic system. They found the breathing mode could effectively couple with incident co-frequency THz pulse and form a phonon-polariton. This quasi-bosonic particle could then generate far-field electro-magnetic radiation with monochromatic frequency comparable to the phonon mode. They regulated the radiation via the spin-phonon interaction […]
A superconducting silicon-photonic chip for quantum communication
Nanowerk November 1, 2021 A key element for achieving discrete-variable QKD is a single-photon detector. Researchers in China heterogeneously integrated, superconducting silicon-photonic chip. Harnessing the unique high-speed feature of the optical waveguide-integrated superconducting detector, they performed optimal Bell-state measurement (BSM) of time-bin encoded qubits generated from two independent lasers. The optimal BSM enables an increased key rate of measurement-device-independent QKD (MDI-QKD), which is immune to all attacks against the detection system and hence provides the basis for a QKD network with untrusted relays. Together with the time-multiplexed technique, they enhanced the sifted key rate by almost one order of magnitude. […]
Researchers develop broadband spintronic-metasurface terahertz emitters with tunable chirality
Phys.org October 26, 2021 Researchers in China made laser-driven terahertz emitters, consisting of metasurface-patterned magnetic multilayer heterostructures that can overcome the shortcomings of the conventional approaches. They have demonstrated the efficient generation and manipulation of broadband chiral terahertz waves. The emitter’s ellipticity can reach >0.75 over a broad terahertz bandwidth (1 to 5 THz), it is an efficient source for few-cycle circularly polarized terahertz pulses with stable carrier waveforms, and has flexible control of ellipticity and helicity. They have shown that the terahertz polarization state is dictated by the interplay between laser-induced spintronic-origin currents and the screening charges/currents in the […]