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Category: particle physics – Page 647

Neutrons tap into magnetism in topological insulators at high temperatures

I know that I reported on this a few weeks ago; however, this article shares some additional insights on how this new method will enable more efficient smaller devices including promoting stabilization in Quantum Computing (QC)…

A multi-institutional team of researchers has discovered novel magnetic behavior on the surface of a specialized material that holds promise for smaller, more efficient devices and other advanced technology.

Researchers at the Department of Energy’s Oak Ridge National Laboratory, Massachusetts Institute of Technology and their collaborators used neutron scattering to reveal magnetic moments in hybrid topological insulator (TI) materials at room temperature, hundreds of degrees Fahrenheit warmer than the extreme sub-zero cold where the properties are expected to occur.

The discovery promises new opportunities for next-generation electronic and spintronic devices such as improved transistors and quantum computing technologies. Their research is discussed in a paper published in the journal Nature.

Quantum Swing: a pendulum that moves forward and backwards at the same time

One of those freaky states of Quantum. Wild.

Two-quantum oscillations of atoms in a semiconductor crystal are excited by ultrashort terahertz pulses. The terahertz waves radiated from the moving atoms are analyzed by a novel time-resolving method and demonstrate the non-classical character of large-amplitude atomic motions.

The classical pendulum of a clock swings forth and back with a well-defined elongation and velocity at any instant in time. During this motion, the total energy is constant and depends on the initial elongation which can be chosen arbitrarily. Oscillators in the quantum world of atoms and molecules behave quite differently: their energy has discrete values corresponding to different quantum states. The location of the atom in a single quantum state of the oscillator is described by a time-independent wavefunction, meaning that there are no oscillations.

Oscillations in the quantum world require a superposition of different quantum states, a so-called coherence or wavepacket. The superposition of two quantum states, a one-phonon coherence, results in an atomic motion close to the classical pendulum. Much more interesting are two-phonon coherences, a genuinely non-classical excitation for which the atom is at two different positions simultaneously. Its velocity is nonclassical, meaning that the atom moves at the same time both to the right and to the left as shown in the movie. Such motions exist for very short times only as the well-defined superposition of quantum states decays by so-called decoherence within a few picoseconds (1 picosecond = 10-12 s). Two-phonon coherences are highly relevant in the new research area of quantum phononics where tailored atomic motions such as squeezed and/or entangled phonons are investigated.

An elastomer that behaves like an artificial muscle

(Phys.org)—Animal muscle needs to be strong enough to endure strain; it must also be flexible and elastic; and it is self-healing. Finding a polymer that has all of these properties has proved challenging. However, researchers from Stanford, Nanjing University, UC Riverside, Harvard, and the University of Colorado have reported the synthesis of an elastomer that mimics the properties of animal muscle. Their polymer, is also stable at room temperature and not sensitive to water. Their work appears in Nature Chemistry.

Efforts to create polymers that mimic the properties of biological muscle have come short of being practically useful. Often the bonding involved in making these polymers must be sufficiently strong to serve as actuators, but weak enough for reversible self-healing. Many models, to date, involve hydrogen bonding, but are sensitive to water. Li, et al. have, instead, exploited metal-ligand interactions as a way to mimic muscle properties.

The ligand 2,6-pyridinedicarboxamide (pdca)binds to Fe(III) via the pyridyl nitrogen and the nitrogen and oxygen on the carboxamides. Two pdca molecules coordinate to one Fe(III) atom through six coordination sites. Two of the sites are strong bonds (the pyridyl), two sites are “medium” strength bonds (the amides), and two are weak bonds (the carboxyl). Calculations of bond strength show that the strong bonds are similar to covalent bonds, while the weak Fe-O bonds are similar to hydrogen bonding. This multi-bonding structure, as it turns out, provides an excellent framework for making an elastomer.

Iridium Oxide Nanoparticles Used to Harvest Hydrogen

Researchers from Argonne National Laboratory developed a first-principles-based, variable-charge force field that has shown to accurately predict bulk and nanoscale structural and thermodynamic properties of IrO2. Catalytic properties pertaining to the oxygen reduction reaction, which drives water-splitting for the production of hydrogen fuel, were found to depend on the coordination and charge transfer at the IrO2 nanocluster surface. Image: Courtesy of Maria Chan, Argonne National Laboratory

Iridium oxide (IrO2) nanoparticles are useful electrocatalysts for splitting water into oxygen and hydrogen — a clean source of hydrogen for fuel and power. However, its high cost demands that researchers find the most efficient structure for IrO2 nanoparticles for hydrogen production.

A study conducted by a team of researchers at the U.S. Department of Energy’s (DOE’s) Argonne National Laboratory, published in Journal of Materials Chemistry A, describes a new empirical interatomic potential that models the IrO2 properties important to catalytic activity at scales relevant to technology development. Also known as a force field, the interatomic potential is a set of values describing the relationship between structure and energy in a system based on its configuration in space. The team developed their new force field based on the MS-Q force field.

“Before, it was not possible to optimize the shape and size of a particle, but this tool enables us to do this,” says Maria Chan, assistant scientist at Argonne’s Center for Nanoscale Materials (CNM), a DOE Office of Science User Facility.

Quantum logical operations realized with single photons

More insights around the logical quantum gate for photons discovered by Max Planck Institute of Quantum Optics (MPQ). Being able to leverage this gate enables Qubits in transmission and processing can be more controlled and manipulated through this discovery, and places us closer to a stable Quantum Computing environment.

MPQ scientists take an important step towards a logical quantum gate for photons.

Scientists from all over the world are working on concepts for future quantum computers and their experimental realization. Commonly, a typical quantum computer is considered to be based on a network of quantum particles that serve for storing, encoding and processing quantum information. In analogy to the case of a classical computer a quantum logic gate that assigns output signals to input signals in a deterministic way would be an essential building block. A team around Dr. Stephan Dürr from the Quantum Dynamics Division of Prof. Gerhard Rempe at the Max Planck Institute of Quantum Optics has now demonstrated in an experiment how an important gate operation — the exchange of the binary bit values 0 and 1 — can be realized with single photons. A first light pulse containing one photon only is stored as an excitation in an ultracold cloud of about 100,000 rubidium atoms.

An experiment seeks to make quantum physics visible to the naked eye

Predictions from quantum physics have been confirmed by countless experiments, but no one has yet detected the quantum physical effect of entanglement directly with the naked eye. This should now be possible thanks to an experiment proposed by a team around a theoretical physicist at the University of Basel. The experiment might pave the way for new applications in quantum physics.

Quantum physics is more than 100 years old, but even today is still sometimes met with wonderment. This applies, for example, to entanglement, a quantum physical phenomenon that can be observed between atoms or photons (light particles): when two of these particles are entangled, the physical state of the two particles can no longer be described independently, only the total system that both particles form together.

Despite this peculiarity, entangled photons are part of the real world, as has been proven in many experiments. And yet no one has observed entangled photons directly. This is because only single or a handful of entangled photons can be produced with the available technology, and this number is too low for the to perceive these photons as light.

New Model Could Show That Stephen Hawking Is Right About Black Holes

One of the longest standing mysteries of black holes is what happens to stuff when it falls inside. Information can’t move faster than light, so it can’t escape a black hole, but we know that black holes shrink and evaporate over time, emitting Hawking radiation. This has troubled scientists for 40 years. Information can’t simply vanish.

Now, physicists Kamil Brádler and Chris Adami, from the University of Ottawa and Michigan State University respectively, have been able to show that the information is not at all lost, but is transferred from the black holes into the aforementioned Hawking radiation, potentially solving a long-standing mystery of cosmology.

Over 40 years ago, Stephen Hawking put forward the idea that although nothing can escape a black hole, there should be a certain amount of particles emitted from the outer edge of the black hole’s event horizon. This emission would over time steal energy from a black hole, causing it to evaporate and shrink.

Theorists perplexed

Physicists may soon know if a potential new subatomic particle is something beyond their wildest dreams — or if it exists at all.

Hints of the new particle emerged last December at the Large Hadron Collider. Theorists have churned out hundreds of papers attempting to explain the existence of the particle —assuming it’s not a statistical fluke. Scientists are now beginning to converge on the most likely explanations.

“If this thing is true, it’s huge. It’s very different than what the last 30 years of particle physics looked like,” says theoretical physicist David Kaplan of Johns Hopkins University.