Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: particle physics – Page 325

Abstract: A central goal of condensed-matter physics is to understand how the diverse electronic and optical properties of crystalline materials emerge from the wavelike motion of electrons through periodically arranged atoms. However, more than 90 years after Bloch derived the functional forms of electronic waves in crystals [1] (now known as Bloch wavefunctions), rapid scattering processes have so far prevented their direct experimental reconstruction. In high-order sideband generation [2–9], electrons and holes generated in semiconductors by a near-infrared laser are accelerated to a high kinetic energy by a strong terahertz field, and recollide to emit near-infrared sidebands before they are scattered. Here we reconstruct the Bloch wavefunctions of two types of hole in gallium arsenide at wavelengths much longer than the spacing between atoms by experimentally measuring sideband polarizations and introducing an elegant theory that ties those polarizations to quantum interference between different recollision pathways. These Bloch wavefunctions are compactly visualized on the surface of a sphere. High-order sideband generation can, in principle, be observed from any direct-gap semiconductor or insulator. We thus expect that the method introduced here can be used to reconstruct low-energy Bloch wavefunctions in many of these materials, enabling important insights into the origin and engineering of the electronic and optical properties of condensed matter.

From: Joseph Costello [view email].

Read more | >

There is a new wonder material in town, and its name is graphene. Since it was first successfully isolated in 2004, graphene, with its honeycomb-like 2D structure and its wide gamut of interesting properties, has been keenly studied by material scientists.

This naturally transparent 1 millimeter thick lattice of carbon atoms has multiple applications and could even one day potentially solve the world’s water crisis.

The faith in the material is so strong that, according to numbers projected by Fortune Business Insights, its market value will be $2.8 billion in 2027.

Read more | >

For the first time ever, a manmade object has entered the Sun’s outer atmosphere, the corona, which inexplicably is thousands of times hotter than our star’s surface (or photosphere).

Researchers led by a team at the University of Michigan in Ann Arbor were able to predict where the Sun’s upper atmosphere began, and the probe was able to penetrate it for roughly five hours. The Parker probe was not only able to fly through the Sun’s atmosphere but was also able to sample particles and magnetic fields there, says NASA.

“Flying so close to the Sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere — the corona — that we never could before,” Nour Raouafi, the Parker project scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, said in a statement. “We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.”

On April 28, 2021, during its eighth flyby of the Sun, Parker Solar Probe encountered the specific magnetic and particle conditions some 8.1 million miles above the solar surface, NASA reports. That point, known as the Alfvén critical surface, marks the end of the solar atmosphere and beginning of the solar wind, says NASA.

The surface of the Sun is about 6,000 Celsius, Justin Kasper, the first author of a paper detailing the research in the journal Physical Review Letters, and a professor of climate and space sciences at the University of Michigan in Ann Arbor, told me. Above that, the temperature rises to more than a million degrees, he says.

Continue reading “NASA’S Parker Solar Probe Touches The Sun’s Searing Upper Atmosphere” | >

Can information become a source of energy? Scientists from Simon Fraser University (SFU) in Canada devised an ultrafast engine that claims to operate on information, potentially opening up a groundbreaking new frontier in humanity’s search for new kinds of fuel. The study, published in Proceedings of the National Academy of Sciences (PNAS), describes how the researchers turned the movements of tiny particles into stored energy.

Practical demon-keeping

How would an information engine even work? The idea for such a contraption, which at first sounds like it would break the laws of physics, was first proposed by the Scottish scientist James Clerk Maxwell back in 1867. Colorfully named “Maxwell’s demon,” such a machine would theoretically achieve something akin to perpetual motion. Maxwell’s thought experiment was meant to show that it may be possible to violate the second law of thermodynamics, which basically states that the amount of entropy, or disorder, always increases.

Read more | >

Nearly a century after Italian physicist Ettore Majorana laid the groundwork for the discovery that electrons could be divided into halves, researchers predict that split photons may also exist, according to a study from Dartmouth and SUNY Polytechnic Institute researchers.

The finding that the building blocks of light can exist in a previously-unimaginable split form advances the fundamental understanding of light and how it behaves.

The theoretical discovery of the split photon – known as a “Majorana boson” – was published in Physical Review Letters.

Read more | >

Scientists have made it possible to generate and control quantum states in different physical systems. This control allows scientists to develop powerful new quantum technologies. In addition, it offers a roadmap to test the foundations of quantum physics.

The main challenge is to create quantum states on a larger scale.

In collaboration with the University of Oxford, scientists at Imperial College London, the Niels Bohr Institute, the Max Planck Institute for the Science of Light, and Australian National University have generated and observed non-Gaussian states high-frequency sound waves comprising more than a trillion atoms. Certainly, they transformed a randomly fluctuating sound field in thermal equilibrium to a pattern thrumming with a more specific magnitude.

Read more | >

Superconductivity is the disappearance of electrical resistance in certain materials below a certain temperature, known as “transition temperature.” The phenomenon has tremendous implications for revolutionizing technology as know it, enabling low-loss power transmission and maintenance of electromagnetic force without electrical supply. However, superconductivity usually requires extremely low temperatures ~ 30 K (the temperature of liquid nitrogen, in comparison, is 77 K) and, therefore, expensive cooling technology. To have a shot at realizing a low-cost superconducting technology, superconductivity must be achieved at much higher transition temperatures.

Materials scientists have had a breakthrough on this front with crystalline materials containing hydrogen, known as “metal hydrides.” These are compounds formed by a metal atom bonded with hydrogen that have been predicted and realized as suitable candidates for achieving even room-temperature superconductivity. However, they require extremely high pressures to do so, limiting their practical applications.

In a new study published in Chemistry of Materials, a group of researchers led by Professor Ryo Maezono from Japan Advanced Institute of Science and Technology (JAIST) performed to expand the search for high-temperature superconductors, looking for among ternary hydrides (hydrogen combined with two other elements).

Read more | >

WASHINGTON, D.C. — Today, the U.S. Department of Energy (DOE) announced $5.7 million for six projects that will implement artificial intelligence methods to accelerate scientific discovery in nuclear physics research. The projects aim to optimize the overall performance of complex accelerator and detector systems for nuclear physics using advanced computational methods.

“Artificial intelligence has the potential to shorten the timeline for experimental discovery in nuclear physics,” said Timothy Hallman, DOE Associate Director of Science for Nuclear Physics. “Particle accelerator facilities and nuclear physics instrumentation face a variety of technical challenges in simulations, control, data acquisition, and analysis that artificial intelligence holds promise to address.”

The six projects will be conducted by nuclear physics researchers at five DOE national laboratories and four universities. Projects will include the development of deep learning algorithms to identify a unique signal for a conjectured, very slow nuclear process known as neutrinoless double beta decay. This decay, if observed, would be at least ten thousand times more rare than the rarest known nuclear decay and could demonstrate how our universe became dominated by matter rather than antimatter. Supported efforts also include AI-driven detector design for the Electron-Ion Collider accelerator project under construction at Brookhaven National Laboratory that will probe the internal structure and forces of protons and neutrons that compose the atomic nucleus.

Read more | >