Science Daily August 23, 2019 The nano corkscrews are highly sensitive to light: depending on frequency and polarisation, they can strongly enhance it. Usually, the interaction of such nano-antennas with an electromagnetic field is determined using numerical methods. Each helix geometry, however, requires a new numerically expensive calculation. Researchers in Germany have a formula that tells them how a nano-antenna with specific parameters responds to light. This analytical description can be used as a design tool, as it specifies the required geometrical parameters of a nano-helix to amplify electromagnetic fields of desired frequencies or polarisation. The research could have applications […]
Better chemistry through tiny antennae
Phys.org August 29, 2019 Selective bond cleavage via vibrational excitation is the key to active control over molecular reactions. However, the practical implementation in condensed phases have been hampered to date by poor excitation efficiency due to fast vibrational relaxation. Researchers in Japan fabricated tiny gold antennae, each 300 nanometers wide, and illuminated them with infrared lasers. When infrared light of the right frequency was present, the electrons in the antennae oscillated back creating plasmonic resonance. The plasmonic resonance focused the laser’s energy on nearby molecules, which started vibrating. The vibration was further boosted by shaping the waveform of the […]
China’s Quantum Satellite Security Has Been Broken
Next Big Future August 22, 2019 Although quantum key distribution (QKD) security can theoretically be unbreakable, the actual implementations are not perfect and have been broken. In a spree of publications thereafter, an international team of researchers (Norway, Germany) has now demonstrated several methods to successfully eavesdrop on commercial QKD systems based on weaknesses of avalanche photodiodes operating in gated mode. This has sparked research on new approaches to securing communications networks…read more. Open Access TECHNICAL ARTICLE
Compact water harvester sucks H20 from the air
The Engineer August 28, 2019 A team of researchers in the US (UC Berkeley, University of South Alabama) showed that a microporous aluminum-based metal-organic framework, MOF-303, can perform an adsorption–desorption cycle within minutes under a mild temperature swing. These findings were implemented in a new water harvester capable of generating 7-10 litres of water per day. The study demonstrates that creating sorbents capable of rapid water sorption dynamics, rather than merely focusing on high water capacities, is crucial to reach water production on a scale matching human consumption…read more. Open Access TECHNICAL ARTICLE
DARPA uses nature as a muse for new computing model
Defense Systems August 9, 2019 Taking a cue from nature’s efficiency and precision, DARPA is looking for concepts that exploit the interplay between complex dynamical behaviors and intrinsic properties of materials to develop novel computing models for the purpose of tackling current hard computation problems, according to an Aug. 1 solicitation. The two-phase, 18-month program has two technical areas: theory and design, then application development…read more.
Entangling photons generated millions of miles apart
Phys.org August 28, 2019 An international team of researchers (China, USA – Louisiana State University, Texas A&M University, Baylor University, Princeton University, Germany, UK) conducted an experiment to test quantum interference, entanglement, and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by approximately 150 million km. By making the photons indistinguishable in all degrees of freedom, they observed time-resolved two-photon quantum interference with a raw visibility of 0.796, well above the 0.5 classical limit, providing unambiguous evidence of the quantum nature of thermal light. Using the photons with no […]
Graphene-based fabric protects against mosquitoes
Physics World August 28, 2019 Researchers at Brown University investigated the fundamental interactions between graphene-based films and the globally important mosquito species, Aedes aegypti, through a combination of live mosquito experiments, needle penetration force measurements, and mathematical modeling of mechanical puncture phenomena. The results showed that graphene or graphene oxide nanosheet films in the dry state are highly effective at suppressing mosquito biting behavior on live human skin. Behavioral assays indicated that the primary mechanism is not mechanical puncture resistance, but rather interference with host chemosensing. This interference is proposed to be a molecular barrier effect that prevents Aedes from […]
Optical neural network could lead to intelligent cameras
Science Daily August 27, 2019 Researchers at UCLA have made systematic improvements to their earlier work on diffractive optical neural networks, based on a differential measurement technique that mitigates the strict nonnegativity constraint of light intensity. In this differential detection scheme, each class is assigned to a separate pair of detectors, behind a diffractive optical network, and the class inference is made by maximizing the normalized signal difference between the photodetector pairs. Using this differential detection scheme, they numerically achieved blind testing accuracies of 98.54%, 90.54%, and 48.51% for MNIST, Fashion-MNIST, and grayscale CIFAR-10 datasets, respectively. They reduced the crosstalk […]
Researchers reveal ultra-fast bomb detection method that could upgrade airport security
EurekAlert August 29, 2019 Paper spray mass spectrometry is a rapid and sensitive tool for explosives detection but so far it has only been demonstrated using high resolution mass spectrometry, which bears too high a cost for many practical applications. Researchers in the UK developed a system which uses swabbing material, they call “swab spray” to collect explosives from surfaces. Sensitive detection using swab spray will require a mass spectrometer with a mass resolving power of 4000 or more. The new detection method is able to analyse a wider range of materials than current thermal based detection systems used in […]
Switching electron properties on and off individually
Science Daily August 22, 2019 An international team of researchers (Austria, USA – Rice University, University of Florida, Germany) investigated a material made of palladium, silicon and cerium focusing on the electrons located at the cerium atom and on the conduction electrons, which can move freely through the crystal. The conduction electrons can virtually hide both the spin and the orbital state of the fixed electrons. This means that order is no longer possible. They have developed a system in which the order can be switched on and off individually in relation to two different degrees of freedom that are […]