EurekAlert February 15, 2021 An international team of researchers (UK, Greece, USA – Rice University, Italy) identified and investigated different geometries of line defects in graphene and molybdenum disulfide such as standing collapsed wrinkles, folded wrinkles, and grain boundaries that exhibit distinct strain and doping. They determined the influence of the defects on local stiffness. For wrinkles of similar height, the stiffness of graphene was found to be higher than that of molybdenum disulfide by 10–15% due to stronger in-plane covalent bonding. Defects in graphene predominantly show compressive strain and increased carrier density. Defects in molybdenum disulfide predominantly show tensile […]
Harnessing socially-distant molecular interactions for future computing
Nanowerk February 15, 2021 Researchers in Australia studied the electronic properties of magnesium phthalocyanine (MgPc) sprinkled on a metal surface and demonstrated that the quantum mechanical properties of electrons within the molecules (energy and spatial distribution) are significantly affected by the presence of neighbouring molecules. This effect was observed for intermolecular separation distances of several nanometres. Quantitative analysis of the experimental results and theoretical modelling showed that this interaction was due to mixing between the quantum mechanical orbitals of neighbouring molecules. The molecular orbital mixing leads to significant changes in electron energies and electron distribution symmetries. The long range of […]
International study reveals exceptional property of next generation optical fibers
EurekAlert February 15, 2021 The elastic backscattering of light in optical fiber is a fundamental phenomenon that sets the ultimate performance of several fiber systems such as gyroscopes and bidirectional transfer links. Until now, efforts to reduce the backscattering coefficient have yielded limited results. An international team of researchers (Canada, UK) measured backscattering from a low-loss antiresonant hollow-core fiber and showed that it is more than 40 dB below reported values in silica-core fiber and hollow-core photonic bandgap fiber. The record-low level of −118dB/m measured with their optical frequency-domain reflectometer is in good agreement with simulations in which they assumed […]
Light used to detect quantum information stored in 100,000 nuclear quantum bits
Phys.org February 15, 2021 An international team of researchers (UK, France) injected a ‘needle’ of highly fragile quantum information in a ‘haystack’ of 100,000 nuclei. By using lasers to control an electron, they could use that electron to control the behavior of the haystack, making it easier to find the needle. By controlling the collective state of the 100,000 nuclei, they were able to detect the existence of the quantum information as a ‘flipped quantum bit’ at an ultra-high precision of 1.9 parts per million: enough to see a single bit flip in the cloud of nuclei. Using this technique, […]
A performance leap for graphene modulators in next generation datacom and telecom
Nanowerk February 16, 2021 Electro-absorption (EA) waveguide-coupled modulators are essential building blocks for on-chip optical communications. Compared to state-of-the-art silicon devices, graphene-based EA modulators promise smaller footprints, larger temperature stability, cost-effective integration, and high speeds. However, combining high speed and large modulation efficiencies in a single graphene-based device has remained elusive so far. An international team of researchers (Spain, Italy, Belgium) overcame this fundamental trade-off by demonstrating the 2D-3D dielectric integration in a high-quality encapsulated graphene device. They integrated hafnium oxide and two-dimensional hexagonal boron nitride within the insulating section of a double-layer graphene EA modulator. This combination of materials […]
Quantum Theory May Twist Cause And Effect Into Loops, With Effect Causing The Cause
Science Alert February 14, 2021 Quantum correlations violating Bell inequalities defy satisfactory causal explanations within the framework of classical causal models. The first challenge has been addressed through the recent development of intrinsically quantum causal models, allowing causal explanations of quantum processes – provided they admit a definite causal order, i.e., have an acyclic causal structure. An international team of researchers addresses causally nonseparable processes and offers a causal perspective on them through extending quantum causal models to cyclic causal structures. Among other applications of the approach, it is shown that all unitarily extendible bipartite processes are causally separable and […]
Researchers explore using light to levitate discs in the mesosphere
Phys.org February 15, 2021 To improve weather prediction sensors need to be sent to mesosphere. The satellites and rockets currently used have problems as the air is too thick and friction and heat would make long-duration flights impractical. Researchers at the University of Pennsylvania constructed and demonstrated light-driven levitation of macroscopic polymer films with nanostructured surface as candidates for long-duration near-space flight. The disks were made of 0.5-micron-thick mylar film coated with carbon nanotubes on one side. When illuminated with light intensity comparable to natural sunlight, the polymer disk heats up and interacts with incident gas molecules differently on the […]
Scientists manipulate magnets at the atomic scale
Science Daily February 12, 2021 An international team of researchers (the Netherlands, Ukraine, Russia, Belgium, UK) shows that light-driven phonons can be utilized to coherently manipulate macroscopic magnetic states. Intense mid-infrared electric field pulses tuned to resonance with a phonon mode of the archetypical antiferromagnet DyFeO3 induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. Non-thermal lattice control of the magnetic exchange, which defines the stability of the macroscopic magnetic state, allows picosecond coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders. The discovery emphasizes the potential of resonant phonon excitation […]
Quickly identify high-performance multi-element catalysts
Eurekalert February 17, 2021 Many electrochemical reactions go through several steps. Each should be optimized on a catalyst surface if possible, but different requirements apply to each step. With the example of the oxygen reduction reaction, an international team of researchers (Denmark, Germany) showed that for high entropy alloys comprising five or more principal elements, by utilizing a data‐driven discovery cycle, the multidimensionality challenge raised by this catalyst class can be mastered. Iteratively refined computational models predict activity trends around which continuous composition‐spread thin‐film libraries are synthesised. High throughput characterisation datasets are then used as input for refinement of the […]
This robot doesn’t need any electronics
Science Daily February 17, 2021 Pneumatically actuated soft robots are controlled with bulky and expensive electromechanical components. Researchers at UC San Diego have created a soft-legged robot using simple pneumatic circuits without any electronic components. Locomotive gaits are produced using ring oscillators composed of soft valves that generate oscillating signals analogous to biological central pattern generator neural circuits, which are acted upon by pneumatic logic components in response to sensor inputs. The robot requires only a constant source of pressurized air to power both control and actuation systems. The circuits generate walking gaits with three degrees of freedom per leg […]