Lifeboat Foundation

O,.o Circa 2018

Light might have no mass, but it can still push things around. This is known as radiation pressure. Light particles (photons) carry a momentum with them, but how this momentum is transferred is not exactly clear. However, new research has come up with a way to actually study these interactions between light and matter.

An international team constructed a very special experiment to study the momentum of light. Photons carry a tiny momentum and their effect can only be studied cumulatively. Still, there were no devices sensitive enough to measure the effect. This is why it has been so difficult to study how radiation pressure is converted into force or movement.

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Famous medieval poet and author Geoffrey Chaucer once wrote that “‘time and tide wait for no man,” and that certainly rings true whether you’ve still got a ’90s Swatch watch strapped to your wrist, your name is Doc Brown, or you’re a brilliant scientist working on the latest atomic clock design — which employs lasers to trap and measure oscillations of quantum entangled atoms to maintain precise timekeeping.

The official time for the United States is set at the atomic clock located at the National Institute of Standards and Technology in Boulder, Colorado, where this Cesium Fountain Atomic Clock remains accurate to within one second every 300 million years. Its cesium-133 atom vibrates exactly 9, 192, 631, 770 times per second, a permanent statistic that has officially measured one second since the machine’s inception and operational rollout back in 1968.

A team of researchers affiliated with several institutions in the U.K. and one in Saudi Arabia has developed a way to produce jet fuel using carbon dioxide as a main ingredient. In their paper published in the journal Nature Communications, the group describes their process and its efficiency.

As scientists continue to look for ways to reduce the amount of carbon dioxide emitted into the atmosphere, they have increasingly focused on certain business sectors. One of those sectors is the aviation industry, which accounts for approximately 12% of transportation-related carbon dioxide emissions. Curbing carbon emissions in the aviation industry has proved to be challenging due to the difficulty of fitting heavy batteries inside of aircraft. In this new effort, the researchers have developed a chemical process that can be used to produce carbon-neutral jet fuel.

The researchers used a process called the organic combustion method to convert carbon dioxide in the air into jet fuel and other products. It involved using an iron catalyst (with added potassium and manganese) along with hydrogen, citric acid and carbon dioxide heated to 350 degrees C. The process forced the carbon atoms apart from the oxygen atoms in CO₂ molecules, which then bonded with hydrogen atoms, producing the kind of hydrocarbon molecules that comprise liquid jet fuel. The process also resulted in the creation of water molecules and other products.

Particle physicist who shared Nobel for discovering muon neutrinos.

Raise your hand if you ever wanted to get beamed onto the transport deck of the USS Enterprise. Maybe we haven’t reached the point of teleporting entire human beings yet (sorry Scotty), but what we have achieved is a huge breakthrough towards quantum internet.

Led by Caltech, a collaborative team from Fermilab, NASA’s Jet Propulsion Lab, Harvard University, the University of Calgary and AT&T have now successfully teleported qubits (basic units of quantum info) across almost 14 miles of fiber optic cables with 90 percent precision. This is because of quantum entanglement, the phenomenon in which quantum particles which are mysteriously “entangled” behave exactly the same even when far away from each other.

Researchers from Tokyo Metropolitan University have discovered a way to make self-assembled nanowires of transition metal chalcogenides at scale using chemical vapor deposition. By changing the substrate where the wires form, they can tune how these wires are arranged, from aligned configurations of atomically thin sheets to random networks of bundles. This paves the way to industrial deployment in next-gen industrial electronics, including energy harvesting, and transparent, efficient, even flexible devices.

Electronics is all about making things smaller—smaller features on a chip, for example, means more computing power in the same amount of space and better efficiency, essential to feeding the increasingly heavy demands of a modern IT infrastructure powered by machine learning and artificial intelligence. And as devices get smaller, the same demands are made of the intricate wiring that ties everything together. The ultimate goal would be a wire that is only an atom or two in thickness. Such nanowires would begin to leverage completely different physics as the electrons that travel through them behave more and more as if they live in a one-dimensional world, not a 3D one.

In fact, scientists already have materials like carbon nanotubes and transition metal chalcogenides (TMCs), mixtures of transition metals and group 16 elements which can self-assemble into atomic-scale nanowires. The trouble is making them long enough, and at scale. A way to mass produce nanowires would be a game changer.

Light travels at a speed of about 300, 000, 000 meters per second as light particles, photons, or equivalently as electromagnetic field waves. Experiments led by Hrvoje Petek, an R.K. Mellon professor in the Department of Physics and Astronomy examined ideas surrounding the origins of light, taking snapshots of light, stopping light and using it to change properties of matter.

Petek worked with students and collaborators Prof. Chen-Bin (Robin) Huang of the National Tsing Hua University in Taiwan, and Atsushi Kubo of the Tsukuba University of Japan on the experiments. Their findings were reported in the paper, “Plasmonic topological quasiparticle on the nanometre and femtosecond scales,” which was published in the Dec. 24 issue of Nature magazine.

Petek credited graduate student Yanan Dai for his foresight and work in the process.

On the electromagnetic spectrum, terahertz light is located between infrared radiation and microwaves. It holds enormous potential for tomorrow’s technologies: Among other things, it might succeed 5G by enabling extremely fast mobile communications connections and wireless networks. The bottleneck in the transition from gigahertz to terahertz frequencies has been caused by insufficiently efficient sources and converters. A German-Spanish research team with the participation of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has now developed a material system to generate terahertz pulses much more effectively than before. It is based on graphene, i.e., a super-thin carbon sheet, coated with a metallic lamellar structure. The research group presented its results in the journal ACS Nano.

Some time ago, a team of experts working on the HZDR accelerator ELBE were able to show that graphene can act as a frequency multiplier: When the two-dimensional carbon is irradiated with light pulses in the low terahertz frequency range, these are converted to higher frequencies. Until now, the problem has been that extremely strong input signals, which in turn could only be produced by a full-scale particle accelerator, were required to generate such terahertz pulses efficiently.“This is obviously impractical for future technical applications,” explains the study’s primary author Jan-Christoph Deinert of the Institute of Radiation Physics at HZDR. “So, we looked for a material system that also works with a much less violent input, i.e., with lower field strengths.”

For this purpose, HZDR scientists, together with colleagues from the Catalan Institute of Nanoscience and Nanotechnology (ICN2), the Institute of Photonic Sciences (ICFO), the University of Bielefeld, TU Berlin and the Mainz-based Max Planck Institute for Polymer Research, came up with a new idea: the frequency conversion could be enhanced enormously by coating the graphene with tiny gold lamellae, which possess a fascinating property: “They act like antennas that significantly amplify the incoming terahertz radiation in graphene,” explains project coordinator Klaas-Jan Tielrooij from ICN2. “As a result, we get very strong fields where the graphene is exposed between the lamellae. This allows us to generate terahertz pulses very efficiently.”

An especially counter-intuitive feature of quantum mechanics is that a single event can exist in a state of superposition—happening both here and there, or both today and tomorrow.

Such superpositions are hard to create, as they are destroyed if any kind of information about the place and time of the event leaks into the surrounding—and even if nobody actually records this information. But when superpositions do occur, they lead to observations that are very different from that of classical physics, raising questions that spill over into our very understanding of space and time.

Scientists from EPFL, MIT, and CEA Saclay, publishing in Science Advances, demonstrate a state of vibration that exists simultaneously at two different times, and provide evidence of this quantum superposition by measuring the strongest class of quantum correlations between light beams that interact with the vibration.