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Category: particle physics

How materials behave depends on the interactions between countless atoms. You could see this as a giant group chat in which atoms are continuously exchanging quantum information. Researchers from Delft University of Technology in collaboration with RWTH Aachen University and the Research Center Jülich have now been able to intercept a chat between two atoms. They present their findings in Science on May 28, 2021.

Atoms, of course, don’t really talk. But they can feel each other. This is particularly the case for magnetic atoms. “Each atom carries a small magnetic moment called spin. These spins influence each other, like compass needles do when you bring them close together. If you give one of them a push, they will start moving together in a very specific way,” explains Sander Otte, leader of the team that performed the research. “But according to the laws of quantum mechanics, each spin can be simultaneously point in various directions, forming a superposition. This means that actual transfer of quantum information takes place between the atoms, like some sort of conversation.”

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What does quark-gluon plasma—the hot soup of elementary particles formed a few microseconds after the Big Bang—have in common with tap water? Scientists say it’s the way it flows.

A new study, published today in the journal SciPost Physics, has highlighted the surprising similarities between , the first matter thought to have filled the early Universe, and water that comes from our tap.

The ratio between the viscosity of a , the measure of how runny it is, and its density, decides how it flows. Whilst both the viscosity and density of are about 16 orders of magnitude larger than in water, the researchers found that the ratio between the viscosity and density of the two types of fluids are the same. This suggests that one of the most exotic states of matter known to exist in our universe would flow out of your tap in much the same way as water.

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Step aside, Nikon P1000, the new king of zoom is here. It’s an electronic microscope, though, but it can zoom in 100 million times and still keep the subject clear. It’s so impressive, in fact, that it earned a spot in the Guinness World Records.

Although electron microscopes allow scientists to see individual atoms, zooming all that far will not result in a sufficiently clear image. It’s due to the aberrations in the lenses which are corrected with special aberration correctors. But the problem is that you can’t stack those correctors forever.

David Muller and Sol Gruner, physics professors of Cornell University, came up with a new approach that they first introduced back in 2018. Their electron microscope achieves high resolution using a high-powered detector and a technique called ptychography. Thanks to this technique, they could capture in sharp detail even particles that measure down to 0.39 ångströms or 0.039 nanometers (one-billionth of a meter).

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Transmission electron microscopy (TEM) is a technique that involves beaming electrons through a specimen to form an image. This enables the generation of significantly higher resolution than traditional optical microscopes. While the latter devices are typically limited to around 1000x magnification due to the resolving power of visible light, TEM can provide zoom capabilities that are orders of magnitude greater – surpassing even a scanning electron microscope (SEM).

In recent years, TEM instruments have begun to reach extraordinary levels of detail. Spatial resolutions are now edging into the realm of individual atoms, measuring less than 0.0000005 millimetres (mm).

However, TEM is prone to lens aberrations and multiple scattering, limiting its use to samples thin enough to let electrons pass through. The process is technically challenging and requires additional tools to perform. In 2018, researchers at Cornell University offered a potential solution. They built a high-powered detector combined with a new algorithm-driven process called ptychography. This achieved a new record for microscopic resolution, tripling the previous state-of-the-art.

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## SCIENCE ADVANCES • MAY 24, 2021 # *by Vienna University of Technology*

In everyday life, phase transitions usually have to do with temperature changes--for example, when an ice cube gets warmer and melts. But there are also different kinds of phase transitions, depending on other parameters such as magnetic field. In order to understand the quantum properties of materials, phase transitions are particularly interesting when they occur directly at the absolute zero point of temperature. These transitions are called "quantum phase transitions" or a "quantum critical points."

Such a quantum critical point has now been discovered by an Austrian-American research team in a novel material, and in an unusually pristine form. The properties of this material are now being further investigated.

It is suspected that the material could be a so-called Weyl-Kondo semimetal, which is considered to have great potential for quantum technology due to special quantum states (so-called topological states). If this proves to be true, a key for the targeted development of topological quantum materials would have been found.

This surprising result is probably related to the fact that the behavior of electrons in this material has some special features. "It is a highly correlated electron system. This means that the electrons interact strongly with each other, and that you cannot explain their behavior by looking at the electrons individually.

If there are only relatively few free electrons, as is the case in a semimetal, then the Kondo effect is unstable. This could be the reason for the quantum critical behavior of the material: the system fluctuates between a state with and a state without the Kondo effect, and this has the effect of a phase transition at zero temperature.

**Quantum fluctuations could lead to Weyl particles**

The main reason why the result is of such central importance is that it is suspected to be closely connected to the phenomenon of “Weyl fermions.” In solids, Weyl fermions can appear in the form of quasiparticles–i.e. as collective excitations such as waves in a pond. According to theoretical predictions, such Weyl fermions should exist in this material.

We suspect that the quantum criticality we observed favors the occurrence of such Weyl fermions,” says Silke Bühler-Paschen. “Quantum critical fluctuations could therefore have a stabilizing effect on Weyl fermions, in a similar way to quantum critical fluctuations in high-temperature superconductors holding superconducting Cooper pairs together.

It seems to us that certain quantum effects–namely quantum critical fluctuations, the Kondo effect and Weyl fermions–are tightly intertwined in the newly discovered material and, together, give rise to exotic Weyl-Kondo states. These are ‘topological’ states of great stability that, unlike other quantum states, cannot be easily destroyed by external disturbances. This makes them particularly interesting for quantum computers.

Thanks to folkstone design inc. & zoomers of the sunshine coast BC

**Relevant Stories**

https://www.youtube.com/channel/UCpEBFr960dwZqR-9HtCWIcQ

## ORIGINAL PAPER

Wesley T. Fuhrman et al, **Pristine quantum criticality in a Kondo semimetal**, Science Advances (2021). DOI: 10.1126/sciadv.abf9134

https://advances.sciencemag.org/content/7/21/eabf9134

#WeylKondoStates #KondoEffect #QuantumComputers.

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Circa 2016 o.o!

The theory used to be that hydrocarbons were created in “shocks,” or violent stellar events that cause a lot of turbulence and, with the shock waves, make atoms into ions, which are more likely to combine.

The data from the European Space Agency’s Herschel Space Observatory has since proved that theory wrong. Scientists at Herschel studied the components in the Orion Nebula, mapping the amount, temperature and motions for the carbon-hydrogen molecule (CH), the carbon-hydrogen positive ion (CH+) and their parent molecule: the carbon ion (C+).

They found that in Orion, CH+ is emitting light instead of absorbing it, which means that it is warmer than the background gas. This was surprising to scientists because the CH+ molecule is incredibly reactive and needs a high amount of energy to form, so when it interacts with the background hydrogen in the cloud it gets destroyed.

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Cosmic rays are high-energy atomic particles continually bombarding Earth’s surface at nearly the speed of light. Our planet’s magnetic field shields the surface from most of the radiation generated by these particles. Still, cosmic rays can cause electronic malfunctions and are the leading concern in planning for space missions.

Researchers know cosmic rays originate from the multitude of stars in the Milky Way, including our sun, and other galaxies. The difficulty is tracing the particles to specific sources, because the turbulence of interstellar gas, plasma, and dust causes them to scatter and rescatter in different directions.

In AIP Advances, University of Notre Dame researchers developed a to better understand these and other cosmic ray transport characteristics, with the goal of developing algorithms to enhance existing detection techniques.

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As the need for urgent climate solutions grows, scientists want to put more research into a technology known as solar geoengineering — the idea of chemically altering the atmosphere to reflect sunlight away from Earth.

It is seen as a potential method of cooling the planet and offsetting climate change. But could such a technology curtail a climate catastrophe — or become the cause of it?

Those against solar geoengineering fear unintended consequences, including irreversible changes to weather patterns, and many climate activists are wary of using the Earth’s atmosphere as a testing ground. Last month in Sweden, an experiment led by Harvard University researchers was cancelled following opposition by environmental and indigenous groups. Researchers had planned on testing a high-altitude balloon that could be used to disperse reflective aerosol particles into the atmosphere.

In this episode of The Stream, we’ll learn more about solar geoengineering and the debate surrounding it.

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