Lifeboat Foundation

A new review paper on magnetic topological materials introduces a theoretical concept that interweaves magnetism and topology. It identifies and surveys potential new magnetic topological materials and suggests possible future applications in spin and quantum electronics and as materials for efficient energy conversion.

Magnetic topological materials represent a class of compounds whose properties are strongly influenced by the topology of the electronic wavefunctions coupled with their spin configuration. Topology is a simple concept dealing with the surfaces of objects. The topology of a mathematical structure is identical if it is preserved under continuous deformation. A pancake has the same topology as a cube, a donut as a coffee cup, and a pretzel as a board with three holes. Adding spin offers additional structure—a new degree of freedom—for the realization of new states of matter that are not known in non-magnetic materials. Magnetic topological materials can support chiral channels of electrons and spins, and can be used for an array of applications including information storage, control of dissipationless spin and charge transport, and giant responses under external stimuli such as temperature and light.

The review summarizes the theoretical and experimental progress achieved in the field of magnetic topological materials beginning with the theoretical prediction of the quantum anomalous Hall effect without Landau levels, leading to recent discoveries of magnetic Weyl semimetals and antiferromagnetic topological insulators. It also outlines recent tabulations of all magnetic symmetry group representations and topology. As a result, all known magnetic materials—including future discoveries—can be fully characterized by their topological properties. The identification of materials for a specific technological application (e.g., quantum anomalous Hall) is straightforward.

Do two promising structural materials corrode at very high temperatures when in contact with “liquid metal fuel breeders” in fusion reactors? Researchers of Tokyo Institute of Technology (Tokyo Tech), National Institutes for Quantum Science and Technology (QST), and Yokohama National University (YNU) now have the answer. This high-temperature compatibility of reactor structural materials with the liquid breeder—a lining around the reactor core that absorbs and traps the high energy neutrons produced in the plasma inside the reactor—is key to the success of a fusion reactor design.

Fusion reactors could be a powerful means of generating clean electricity, and currently, several potential designs are being explored. In a fusion reactor, the fusion of two nuclei releases massive amounts of energy. This energy is trapped as heat in a “breeding blanket” (BB), typically a liquid lithium alloy, surrounding the reactor core. This heat is then used to run a turbine and generate electricity. The BB also has an essential function of fusion fuel breeding, creating a closed fuel cycle for the endless operation of the reactors without fuel depletion.

The operation of a BB at extremely high temperatures over 1,173 K serves the attractive function of producing hydrogen from water, which is a promising technology for realizing a carbon-neutral society. This is possible because the BB heats up to over 1,173 K by absorbing the energy from the fusion reaction. At such temperatures, there is the risk of structural materials in contact with the BB becoming corroded, compromising the safety and stability of the reactors. It is thus necessary to find structural materials that are chemically compatible with the BB material at these temperatures.

Both quantum computing and machine learning have been touted as the next big computer revolution for a fair while now.

However, experts have pointed out that these techniques aren’t generalized tools – they will only be the great leap forward in computer power for very specialized algorithms, and even more rarely will they be able to work on the same problem.

Continue reading “What’s Inside a Black Hole? Quantum Computers May Be Able to Simulate It” »

Our new US2QC program aims to determine if an underexplored approach to quantum computing is capable of achieving operation much faster than conventional predictions. https://ow.ly/ABgY50I1qEq

Researchers at the National Institute of Standards and Technology (NIST) have constructed and tested a system that allows commercial electronic components—such as microprocessors on circuit boards—to operate in close proximity with ultra-cold devices employed in quantum information processing. That design allows four times as much data to be output for the same number of connected wires.

In the rising excitement about quantum computing, it can be easy to overlook the physical fact that the data produced by manipulation of quantum bits (qubits) at cryogenic temperatures a few thousandths of a degree above absolute zero still has to be initiated, read out, and stored using conventional electronics, which presently work only at room temperature, several meters away from the qubits. This separation has obstructed development of quantum computing devices that outperform their classical counterparts.

That extra distance between the quantum computing elements and the external electronics requires extra time for signals to travel, which also causes signals to degrade. In addition, each (comparatively very hot) wire needed to connect the electronics to the cryogenic components adds heat, making it hard to maintain the ultracold temperature required for the quantum devices to work.

Circa 2021

Small, affordable, ‘plug-and-play’ quantum computing is one step closer. An Australian startup has won $13 million to make its diamond-based computing cores shine. Now it needs to grow.

ANU research spinoff Quantum Brilliance has found a way to use synthetic diamonds to drive quantum calculations. Now it’s on a five-year quest to produce commercially viable Quantum Accelerators. The goal is a card capable of being plugged into any existing computer system similar to the way graphics cards are now.

Continue reading “Small, diamond-based quantum computers could be in our hands within five years” »

The trial started in March 2021 and was completed in early 2022.

Schran agrees. “This new mechanism of friction is definitely very interesting and exciting,” he says. “But what is missing in my opinion, is a clear benchmark measurement.” Quantifying, for instance, how friction changes based on water’s interaction with single versus multiple layers of carbon atoms could go a long way to fully verifying the new theory, which predicts that greater numbers of electrons in the multilayered carbon will boost friction.

The study team is already progressing along this path and dreaming of what lies beyond. They are hoping to eventually test their theory with flowing liquids other than water, and nanotubes composed of elements besides carbon. In such cases, molecules in the liquid and the electrons within nanotube walls would follow different patterns of interaction, possibly leading to changes in the degree of quantum friction. Lydéric Bocquet says that it may even be possible to control the amount of friction a flowing liquid experiences by constructing nanotubes with electron behavior explicitly in mind.

The new study sets the stage for years of complex exploration by experimental and theoretical physicists alike and, according to Kavokine, also signals a fundamental shift in how physicists should think about friction. “Physicists have long thought that it is different at the nanoscale, but this difference was not so obvious to find and describe,” he says. “They were dreaming about some quantum behavior arising at these scales—and now we have shown how it does.”