#superconductor

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Rare i-wave State in PtBi2 Open New Path for Majorana Qubits

Quantum Leap: PtBi2 Has Ultra-Rare “i-wave” Superconductivity

PtBi2 exhibits a novel superconductivity discovered by an international collaboration. Using cutting-edge spectroscopic approaches, the researchers identified i-wave pairing symmetry, a rare electronic state that could revolutionise topological quantum computing.

Solving the Symmetry Issue

Superconductivity is usually defined by electron pairing and flow. In “textbook” materials like niobium and lead, electrons create s-wave pairs with zero angular momentum. More uncommon materials with d-wave symmetry, such the high-temperature cuprate superconductors discovered decades ago, contain “nodes” where superconductivity practically disappears in the gap.

Beyond these recognised states, PtBi2 discovery is significant. In the Weyl semimetal PtBi2, they identified i-wave pairing, which corresponds to l=6 angular momentum. Never before has unconventional superconductivity above the d-wave level (l=2) been detected spectroscopically. The material's intricate symmetry comes from its trigonal crystal structure and point group symmetry, A2.

Atomic precision

Discovery was made utilising angle-resolved photoemission spectroscopy (ARPES) to map electron energy and momentum. Using a low-energy laser source (6 eV), the scientists achieved “unprecedented clarity” by focussing on Fermi arcs, which are surface-only electronic states.

Their results show that the PtBi2 surface becomes superconducting below 10 K, whereas the rest of the material remains metallic. The researchers found Fermi arc-centered gap nodes in this superconducting surface. These nodes are more than physical oddities—they define the substance's unusualness.

The Majorana Link

These nodes greatly impact topological matter. Because PtBi2's Fermi-arc states are non-degenerate and chiral, the superconducting order parameter changes along the arc, creating surface Majorana cones.

Majorana fermions interact with their own antiparticles. Researchers believe these cones create powerful, zero-energy Majorana flat bands near surface step or hinge borders. This makes PtBi2 surfaces uncommon, topological i-wave superconductors and a viable material platform for generating and manipulating Majorana bound states.

A “anomalous” topological superconductor appears on PtBi2. More than four Majorana cones are needed in a typical 2D system. However, PtBi2 features six Majorana cones on top and six on bottom, a 3D system-only layout.

Challenges and Quantum Computing Path

Despite the excitement, PtBi2 is not ready for quantum computers yet, experts said. One challenge is the coexistence of gapless Majorana states with a metallic bulk, which may interfere with the sensitive quantum information in Majorana modes.

Ultrathin samples to remove bulk modes or a magnetic field to disturb time-reversal symmetry are among the group's suggestions. If this symmetry is disrupted, Majorana cones may “gap out” and leave zero-dimensional bound states or chiral Majorana edge modes suitable for topological quantum computation's “braiding” operations.

New Material Science Chapter

Since i-wave superconductivity was discovered, PtBi2 is now a special material. While there exists potential for intrinsic topological superconductivity in materials like Sr2​RuO4​ or heavy-fermion systems, experimental results have been inconsistent. This study's ARPES data clarity provides perhaps the strongest evidence for an intrinsic topological superconductor.

As scientists evaluate these discoveries, they will likely focus on determining the mechanism behind this rare i-wave combination. Cuprates require strong electron interactions, but PtBi2's extremely delocalised electronic states suggest a different, unexplained source for its unique properties.

You can understand these superconducting states by comparing electron pairing to a staged dance. A typical s-wave superconductor's dancers appear to move in a perfect circle from every angle. D-wave superconductors dance more intricately, like a flower with four petals, stopping at four nodes. In the recently discovered i-wave state of PtBi2, the dance is an intricate, high-frequency geometry with twelve petals, forming a complex motion-stillness pattern that produces the mysterious Majorana particles at its border.

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From value-adds to networking superconductor: how the weird language of tech dulled sport | Sport

Finally, a sector more ludicrously hyped than AI. Speaking to Yahoo Sports recently about the launch of Project B, a startup global women’s basketball league, co-founder Grady Burnett declared that “women’s basketball is growing right now as fast as AI”. Come again? There’s no question that women’s basketball is growing nicely, a development that we should all cheer: this year’s WNBA season was…

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American Superconductor: Again To Earth After Runaway Momentum

American Superconductor: Again To Earth After Runaway Momentum

American Superconductor: Again To Earth After Runaway Momentum

[ilearnedthistodaysblog]

#1065 What is a superconductor?

What is a superconductor? It is a state of matter for a material where there is zero resistance to electricity. We need to start by looking at what electrical resistance is. Electrical resistance is, rather obviously, a resistance to the flow of electricity. An electric current results when electrons flow from an area with a large number of electrons to an area with a low number of electrons. This difference is called the electric difference potential. Just like wind flows from an area of high pressure to an area of low pressure, electrons move in the same way. Electrons orbit around atoms, but when they are given enough energy, they can jump off their atom and move to another one. This is how electricity is transferred. Each electron jumps to the next atom, transferring its energy to an electron on that atom which jumps on and continues the transfer. When the electrons flow, they don’t move in a straight line. They are almost like balls on a pinball machine, bouncing off all of the pegs. In this case, the pegs are the nuclei of the atoms that make up the material that the electrons are moving through. Occasionally, the electrons hit a nuclei and each time they hit a nuclei, they release their energy as heat. Sometimes, such as with the heating element in a toaster, you want this heat because it can be used to cook toast, but most often you don’t. Resistance is also influenced by the size and the shape of the material the current is being passed through. An analogy of water through a pipe is often used. Water at the sides of the pipe flows more slowly than water in the middle because it is coming into contact with the pipe and friction produces resistance, slowing the water down. Water also flows more quickly through wide pipes than it does narrow ones and through straight pipes than through twisted ones. A longer pipe will have more resistance than a shorter pipe as well. All of these things are the same with electricity and can increase the resistance. The molecules get in the way of the electrons and cause resistance, so it could be assumed that a denser material with more molecules would have more resistance than a less dense material, but this isn’t the case. Some dense materials, such as silver, have electrons that can more and transfer energy more easily than some less dense materials, such as wood. So, what is a superconductor? A superconductor is a state where there is zero electrical resistance. To get electrons to move across a material requires energy, which is generated from burning oil, or sunlight, or other ways, and this energy is transferred across the material. Every time an electron hits a nuclei, its energy is lost as heat and the efficiency of the material goes down. If the power source is removed, the remaining power will be lost as heat until there is nothing left. Because a superconductor has zero resistance, the energy is never lost and will be transferred through the material forever. A superconductor has zero resistance and 100% efficiency. To achieve that, it has to be cooled down to the point where its atoms and electrons don’t move the way they do in normal materials. At low temperatures, almost to the point of absolute zero, which is -273.15 ℃, the atoms stop moving. All atoms vibrate at a different frequency, and this vibration means there is more chance that they will get in the way of electrons. With no vibration, that chance is reduced to almost zero. The second thing that happens is the movement of the electrons becomes very stable. At normal temperatures, the electrons bounce all over the place until they transfer their energy or hit the nucleus of an atom. In a superconductor, the electrons form pairs called Cooper pairs that spin at the same speed as each other, but in opposite directions. They move in sync with each other, avoiding the nuclei, and passing on the current without any loss. Getting a material down to the temperatures required for a superconductor is very difficult and very expensive. Recent research has shown that some materials can become superconductors at -196℃, which is still pretty low but much easier to achieve and maintain than close to absolute zero. If this becomes possible and scalable, the possibilities are limitless. And this is what I learned today. Image By Henry Mühlpfordt - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9491383 Sources https://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance https://www.livescience.com/superconductor https://builtin.com/hardware/superconductor https://telgurus.co.uk/what-causes-or-reduces-resistance-in-a-material https://www.bbc.co.uk/bitesize/guides/zqk9v9q/revision/2 https://www.quora.com/Is-electricity-the-flow-of-energy-through-electrons-or-do-electrons-flow-by-itself https://en.wikipedia.org/wiki/Electric_charge https://www.britannica.com/story/why-are-some-metals-more-conductive-than-others https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance https://www.reddit.com/r/askscience/comments/114m25/on_an_atomic_level_what_makes_certain/ Read the full article

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Scientists Identify The World's First 'Unconventional' Superconductor Found in Nature

Few materials have the uncanny talent of carrying a current with virtually no resistance in what is known as superconductivity.

Few materials have the uncanny talent of carrying a current with virtually no resistance in what is known as superconductivity. The smallest handful of those can be found in nature. Scientists have discovered that one material with a formula found in nature is capable of superconducting at low temperatures without using the typical quantum trickery, making it the first unconventional superconductor of its kind.

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Quick kinda exciting update:

I have shown a (very) rough range for critical temperature (at least, for the temperature where it reacts to a magnet) and i believe the magnetic effect is caused only in part by innate diamagnetism but rather by induction.

The critical temperature is between 80 and 120 degrees C, (based on my accidentally pouring the very hot powder onto plastic that melted, then realizing i could probably measure the temperature by what things it melts, then testing a bunch of substances (mostly plastics) to get a good estimate of melting point) so that's good. I have little doubt that further research can raise this temperature even higher. The second point of interest from recent studies is that i think that i was wrong about the cause of the reaction to a magnet. I think it's some sort of static-like effect, caused not from typical static, but rather from induced electric current that then causes the particles to become charged and fly away from the plastic card as it becomes charged itself. I tried seeing if it were somehow just normal static by using a piece of copper (as non-magnetic metal), a piece of cloth, and another piece of plastic against the plastic card i was using as my testing surface and found there to be a very slight effect, but it was extremely minor compared to moving a strong magnet under the powder. This does seem to indicate that the testing has always only worked because of the material that i was using under the particles, however it does also indicate that the particles are electrically conductive, though this phenomenon alone does not indicate superconductivity. The fact that the effect is (likely) not from strong diamagnetism is not a good sign, but honestly i'm currently quite confused. In order to get better results, i'll be trying with the powder on different surfaces, including but not limited to flat sheets of copper, paper, and aluminium.

This quick update went much longer than intended. Anyway, the first result (about temperature) is the one i'm most excited about, but the second one will be the focus of more research once i have free time again