Science Daily March 16, 2021 A team of researchers in the US (Michigan Technological University, Iowa State University) used a predictive quantum many-body theory that considers electron-electron interactions. The team found that chromium-doped nanowires with a germanium core and silicon shell can be an antiferromagnetic semiconductor. The origin of antiferromagnetic spin alignments between Cr is attributed to the super exchange interaction mediated by the pz orbitals of the Ge atoms that are bonded to Cr. A weak spin–orbit interaction in this material, suggested a longer spin coherence length. The spin-dependent quantum transport calculations in the Cr-doped nanowire junction revealed a […]
Author Archives: Hema Viswanath
Detecting photons transporting qubits without destroying quantum information
Phys.org March 25, 2021 Photons that carry qubits over long distances are easily deflected from their path in the air or absorbed in glass fibers—and suddenly, the quantum information is lost. An international team of researchers (Germany, Spain) has developed a physical protocol that can indicate whether the qubit is lost at intermediate stations of the quantum transmission. If this is the case, the transmitter can send the qubit again with significantly less delay than if the loss is noticed only at the receiving end. The protocol only detects the qubit photon and not measure it. They achieved a nondestructive […]
Global Warming Is ‘Fundamentally’ Changing The Structure of Our World’s Oceans
Science Alert March 25, 2021 An international team of researchers (Australia, UK, Germany, France, USA – Carnegie Mellon University) used global temperature and salinity observations obtained between 1970 and 2018 with a focus on the summer months. They found that the barrier layer separating the ocean surface and the deep layers had strengthened world-wide at a much larger rate than previously thought and contrary to their expectations, winds strengthened by climate change had also acted to deepen the ocean surface layer by five to 10 metres per decade over the last half century. The oceans play a crucial role in […]
Looking at optical Fano resonances under a new light
Phys.org March 19, 2021 Fano resonances are conventionally understood as sharp spectral features that can be excited only by plane waves with specific frequencies and incident angles. Researchers at the City University of New York proved that they can be tailored to resonate only when excited by a frequency, polarization, and wavefront of choice. This generalization reveals that Fano systems are characterized by eigenwaves that scatter to their time-reversed image upon reflection. They showed that the selected wavefront is locally retroreflected everywhere across the device. These results show that conventional Fano resonances are a subset of a broader dichroic phenomenon […]
A material that is superconductive at room temperature and lower pressure
Phys.org March 22, 2021 Previously a team of researchers in the US (University of Rochester, SUNY Buffalo, University of Nevada) had shown that when a hydrogen-rich compound was squeezed to 267 GPa it became superconductive. In the new research the same team combined hydrogen with yttrium instead of carbon and sulfur greatly reducing the pressure. Two diamond anvils used to create the pressure were placed slightly apart with hydron gas and a sample of yttrium in its solid state between them. To prevent oxidation of the yttrium a sheet of palladium was placed between them. It also served as a […]
Optical fiber could boost power of superconducting quantum computers
Science Daily March 24, 2021 In superconducting quantum processors, each qubit is individually addressed with microwave signal lines that connect room-temperature electronics to the cryogenic environment of the quantum circuit. The complexity and heat load associated with the multiple coaxial lines per qubit limits the maximum possible size of a processor to a few thousand qubits. A team of researchers in the US (NIST, Boulder CO, University of Colorado) has introduced a photonic link using an optical fibre to guide modulated laser light from room temperature to a cryogenic photodetector, capable of delivering shot-noise-limited microwave signals directly at millikelvin temperatures. […]
Researchers’ algorithm designs soft robots that sense
MIT News March 22, 2021 Unlike rigid robots which operate with compact degrees of freedom, soft robots must reason about an infinite dimensional state space. This continuum state space presents significant challenges when working with a finite set of discrete sensors. Sensor location has a profound downstream impact on the richness of learned models for robotic tasks. Researchers at MIT present a novel representation for co-learning sensor placement and complex tasks. They developed a neural architecture which processes on-board sensor information to learn a salient and sparse selection of placements for optimal task performance. They evaluated their model and learning […]
Scientists observe complex tunable magnetism in a topological material
Science Daily March 23, 2021 An international team of researchers (USA – Ames Laboratory, Iowa State University, University of Missouri Research Reactor, Oak Ridge National Laboratory, Harvard University, Canada) discovered that EuIn2As2 has collinear antiferromagnetic order where the magnetic moment direction determines either a topological-crystalline-insulator phase supporting axion electrodynamics or a higher-order-topological-insulator phase with chiral hinge states. They used neutron diffraction, symmetry analysis, and density functional theory results to demonstrate that EuIn2As2 exhibits low-symmetry helical antiferromagnetic order which makes it a stoichiometric magnetic topological-crystalline axion insulator protected by the combination of a 180∘ rotation and time-reversal symmetries: C2×T=2′. Surfaces protected […]
Toward perdurable flexible electronics
Nanowerk March 23, 20212 In wearable electronics, to acquire stability and simultaneously preserve stretchability, sensitivity, and scalability is of high significance yet challenging for practical device applications. Researchers in Japan developed a kirigami-structured graphene–polymer hybrid nanocomposite for strain sensors by a laser direct writing technique on a polyimide sheet. To protect the device, ecoflex polymer was applied as the passivation layer. Depending on the applications, ecoflex grid-wrapped and film-encapsulated have high stretchability and sensitivity. In demonstrations the sensor platform suffered almost no performance degradation even after >60 000 stretching cycle tests due to less strain within the sensor. As proof-of-concept for […]
Tunable smart materials
Science Daily March 22, 2021 Biological molecules in living organisms have a remarkable ability to form self-assembled structures when triggered by an external molecule. Based on this concept researchers in Japan created a tunable system involving poly(sodium acrylate) microparticles that can have one of two types of chemical groups attached. The adjustable parameters x and y refer to the molar percent of microparticles with β-cyclodextrin and adamantyl residues, respectively. The shape of assemblies formed by microparticles was dependent on the residue content. For assemblies to form, x needed to be at least 22.3. As the value of y increased, the […]