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 […]
Researchers discover new way to generate light through use of pre-existing defects in semiconductor materials
Nanowerk October 26, 2021 InGaN LEDs with considerably high indium concentrations remain difficult to manufacture using conventional semiconductor structures. An international team of researchers (Singapore, USA- MIT) leveraged the the formation of pyramids, the intrinsic defects in LED materials. V-pits, which result from naturally-existing dislocations in the material, directly forms indium-rich quantum dots that emit longer-wavelength light. By growing these structures on conventional silicon substrates, the need for patterning or unconventional substrates is further eliminated. The researchers demonstrated visual confirmation of their morphology. In addition to the formation of quantum dots, the nucleation of stacking faults – another intrinsic crystal […]
Scientists fear global ‘cascade’ of climate impacts by 2030
Phys.org October 26, 2021 The report by UK-based policy institute Chatham House drew on the views of more than 200 climate scientists and other specialists to assess which immediate climate hazards and impacts should most concern decision-makers in the coming decade. According to the report the ten “hazard-impact pathways” of greatest near-term concern all relate to Africa or Asia. The vulnerability of the place where they happen means impacts cascade and have knock-on impacts that are global in their nature, or at least cover large regions. Without more aid for adaptation and poverty reduction storm damage and multiple crop failures […]
Shape-shifting materials with infinite possibilities
Phys.org October 22, 2021 Researchers at Harvard University have created structural materials, they call totimorphic materials, that have an arbitrary range of shape-morphing capabilities. By having a neutrally stable unit cell they could separate the geometry of the material from its mechanical response at both the individual and solved the problem of balancing the needs of conformability and rigidity. They connected individual unit cells with naturally stable joints, building 2-D and 3-D structures from individual totimorphic cells. Using both mathematical modeling and real-world demonstrations they showed the material’s shape-shifting ability. One single sheet of totimorphic cells could curve up, twist […]
Stronger than spider silk: Bagworm silk enables strong conducting fibers
Science Daily October 22, 2021 Researchers in Japan combined polyaniline, a conducting polymer that can be easily synthesized, with bagworm silk obtained from a bagworm nest. The composite fibers obtained from the silk and polyaniline were 2 microns in diameter and acted as optical waveguides. They demonstrated that green laser light propagates along these fibers, while remaining confined within each fiber. Using SQUID measurements they determined that the fibers can act as paramagnets. By applying the bagworm silk/polyaniline composite in a field-effect transistor device, the research team also confirmed that the composite fiber is suitable for use in textile transistors. […]
Teaching robots to think like us
Science Daily October 26, 2021 Researchers in Japan have taught a robot to navigate through a maze by electrically stimulating a culture of brain nerve cells connected to the machine. The neurons were grown from living cells and acted as the physical reservoir for the computer to construct coherent signals. The signals are regarded as homeostatic signals, telling the robot the internal environment was being maintained within a certain range and acting as a baseline as it moved freely through the maze. Throughout trials, the robot was continually fed the homeostatic signals interrupted by the disturbance signals until it had […]
US intelligence services see security threat in climate change
Phys.org October 22, 2021 According to the Office of the Director of National Intelligence more extreme weather will increasingly exacerbate a number of risks to US national security interests, from physical impacts that could cascade into security challenges, to how countries respond to the climate challenge. It is driving increased geopolitical tension as countries argue over who should be doing more, cross-border “flashpoints” as countries respond to climate change impact by trying to secure their own interests, and fallout from climate on national stability in some countries. With more than 85 percent of global emissions coming from beyond US borders […]
Top 10 Science and Technology Inventions for the Week of October 22, 2021
01. Intelligent optical chip to improve telecommunications 02. Making progress towards quantum technologies based on magnetic molecules 03. Molecular interfaces for innovative sensors and data storage devices 04. New metalens focuses light with ultra-deep holes 05. Quantum material to boost terahertz frequencies 06. Scientists develop novel ‘shapeshifting’ liquid crystal 07. Tuning transparency and opacity 08. Ultrafast control of quantum materials 09. Ultrafast magnetism: Heating magnets, freezing time 10. Ultrafast optical switching can save overwhelmed datacenters And others… Artificial networks learn to smell like the brain Cooling radio waves to their quantum ground state Unmasking the magic of superconductivity in twisted […]
Artificial networks learn to smell like the brain
MIT News October 18, 2021 A team of researchers in the US (Stanford University, University of Chicago, Columbia University, MIT) constructed a network of artificial neurons comprising an input layer, a compression layer, and an expansion layer — just like the fruit fly olfactory system. They gave it the same number of neurons as the fruit fly system, but no inherent structure: connections between neurons would be rewired as the model learned to classify odors. The scientists asked the network to assign data representing different odors to categories, and to correctly categorize not just single odors, but also mixtures of […]
Cooling radio waves to their quantum ground state
Phys.org October 15, 2021 In standard cryogenic systems thermal decoherence prevents access to the quantum regime for photon frequencies below the gigahertz domain. An international team of researchers (the Netherlands, Germany) engineered two superconducting LC circuits coupled by a photon-pressure interaction and demonstrated sideband cooling of a hot radio frequency (RF) circuit using a microwave cavity. Because of a substantially increased coupling strength, they obtained a large single-photon quantum cooperativity and reduced the thermal RF occupancy by 75% with less than one pump photon. For larger pump powers, the coupling rate exceeds the RF thermal decoherence rate by a factor […]