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Physicists Observe 'Billions of Billions' of Entangled Electrons | Physics – Sci-News.com

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An international team of physicists says they have observed quantum entanglement among ‘billions of billions’ of flowing electrons in thin films of YbRh2Si2, a model strange-metal compound.

In this illustration, one photon (purple) carries a million times the energy of another (yellow). Image credit: NASA / Sonoma State University / Aurore Simonnet.

“Quantum entanglement is the basis for storage and processing of quantum information. At the same time, quantum criticality is believed to drive high-temperature superconductivity,” said co-author Dr. Qimiao Si, a physicist in the Department of Physics and Astronomy at the Center for Quantum Materials at Rice University.

“So our findings suggest that the same underlying physics — quantum criticality — can lead to a platform for both quantum information and high-temperature superconductivity. When one contemplates that possibility, one cannot help but marvel at the wonder of nature.”

In their experiments, Dr. Si and colleagues examined the electronic and magnetic behavior of YbRh2Si2 as it both neared and passed through a critical transition at the boundary between two well-studied quantum phases.

To get the result, the researchers overcame several challenges.

First, they had to develop a highly complex materials synthesis technique to produce ultrapure films of YbRh2Si2.

At absolute zero temperature, the material undergoes a transition from one quantum phase that forms a magnetic order to another that does not. The authors performed terahertz spectroscopy experiments on the films at temperatures as low as 1.4 Kelvin.

The terahertz measurements revealed the optical conductivity of the YbRh2Si2 films as they were cooled to a quantum critical point that marked the transition from one quantum phase to another.

“With strange metals, there is an unusual connection between electrical resistance and temperature,” said senior author Dr. Silke Bühler-Paschen, a physicist in the Institute for Solid State Physics at Technischen Universität Wien and the Department of Physics and Astronomy at the Center for Quantum Materials at Rice University.

“In contrast to simple metals such as copper or gold, this does not seem to be due to the thermal movement of the atoms, but to quantum fluctuations at the absolute zero temperature.”

Atomic-resolution STEM image of the interface between film (top left) and substrate (bottom left), representative enlarged views with simulated overlays (center), and the corresponding unit cells (right). Image credit: Prochaska et al, doi: 10.1126/science.aag1595.

Atomic-resolution STEM image of the interface between film (top left) and substrate (bottom left), representative enlarged views with simulated overlays (center), and the corresponding unit cells (right). Image credit: Prochaska et al, doi: 10.1126/science.aag1595.

To measure optical conductivity, the team shined coherent electromagnetic radiation in the terahertz frequency range on top of the films and analyzed the amount of terahertz rays that passed through as a function of frequency and temperature.

The experiments revealed frequency over temperature scaling, a telltale sign of quantum criticality.

Making the films was even more challenging. To grow them thin enough to pass terahertz rays, the scientists developed a unique molecular beam epitaxy system and an elaborate growth procedure.

Ytterbium, rhodium and silicon were simultaneously evaporated from separate sources in the exact 1-2-2 ratio. Because of the high energy needed to evaporate rhodium and silicon, the system required a custom-made ultrahigh vacuum chamber with two electron-beam evaporators.

“Our wild card was finding the perfect substrate: germanium,” said first author Lukas Prochaska, a graduate student in the Institute for Solid State Physics at Technischen Universität Wien.

“The germanium was transparent to terahertz, and had certain atomic distances (that were) practically identical to those between the ytterbium atoms in YbRh2Si2, which explains the excellent quality of the films.”

“Conceptually, it was really a dream experiment,” Dr. Si said.

“Probe the charge sector at the magnetic quantum critical point to see whether it’s critical, whether it has dynamical scaling.”

“If you don’t see anything that’s collective, that’s scaling, the critical point has to belong to some textbook type of description. But, if you see something singular, which in fact we did, then it is very direct and new evidence for the quantum entanglement nature of quantum criticality.”

The results appear in the journal Science.

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L. Prochaska et al. 2020. Singular charge fluctuations at a magnetic quantum critical point. Science 367 (6475): 285-288; doi: 10.1126/science.aag1595

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A Surprisingly Large Number Of “Stars” You See In The Sky Are Actually Spacecraft – Wonderful Engineering

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Thousands of communication satellites are being designed and launched at a rapid pace. These satellites will have a negative impact on observational astronomy research and are likely to significantly disrupt recreational or traditional cultural stargazing.

If you look up in the sky, you might notice a sequence of bright star-like objects moving in a straight line. Those aren’t stars. They’re Starlink satellites, and they’ll soon be even more noticeable in the dark sky.

Samantha Lawler, assistant professor of astronomy at the University of Regina, recently wrote a piece in The Conversation warning that “one out of every 15 points” of light in the sky could someday be a satellite rather than a star. Moreover, she said he also thinks that satellite companies like Elon Musk’s SpaceX’s Starlink will immensely impact space research.

“This will be devastating to research astronomy and will completely change the night sky worldwide,” she wrote.

Lawler’s forthcoming study will be published in The Astronomical Journal, which will show evidence for the adverse stargazing effects of satellite megaconstellations like SpaceX’s.

Given that firms like SpaceX offer internet to locations around the world that might otherwise be without it, Lawler believes that regulatory agencies should limit the number of visible satellites in orbit.

“Our perspective of the stars will soon be changed forever,” she added if that doesn’t happen.

“We can’t accept the global loss of access to the night sky, which we’ve been able to see and connect with for as long as we’ve been human,” she wrote.

Our orbit is clogged with space debris. Starlink’s satellites have to avoid space junk as well. Will legislators intervene to put a stop to it? If prior responses to existential concerns like climate change are any indication, it will be considered later rather than sooner.

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Dinosaur tail found in Chile stuns scientists – Phys.Org

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Miniature models of the Stegouros elengassen, a species of dinosaur discovred in Patagonia in 2018, is seen on display December 1, 2021 in Santiago.

Chilean paleontologists on Wednesday presented their findings on a dinosaur discovered three years ago in Patagonia which they said had a highly unusual tail that has stumped researchers

The remains of the Stegouros elengassen were discovered during excavations in 2018 at Cerro Guido, a site known to harbor numerous fossils, by a team who believed they were dealing with an already known species of dinosaur until they examined its .

“That was the main surprise,” said Alexander Vargas, one of the paleontologists. “This structure is absolutely amazing.”

“The tail was covered with seven pairs of osteoderms … producing a weapon absolutely different from anything we know in any dinosaur,” added the researcher during a presentation of the discovery at the University of Chile.

The osteoderms—structures of bony plaques located in the dermal layers of the skin – were aligned on either side of the tail, making it resemble a large fern.

Paleontologists have discovered 80 percent of the dinosaur’s skeleton and estimate that the animal lived in the area 71 to 74.9 million years ago. It was about two meters (almost seven feet) long, weighed 150 kilograms (330 pounds) and was a herbivore.

According to the scientists, who published their research in the journal Nature, the animal could represent a hitherto unknown lineage of armored dinosaur never seen in the but already identified in the northern part of the continent.

The remains of a Stegouros elengassen, a new species of dinosaur discovered in Patagonia, is seen on display in Santiago Decembe
The remains of a Stegouros elengassen, a new species of dinosaur discovered in Patagonia, is seen on display in Santiago December 1, 20121.

“We don’t know why (the tail) evolved. We do know that within armored dinosaur groups there seems to be a tendency to independently develop different osteoderm-based defense mechanisms,” said Sergio Soto, another member of the team.

The Cerro Guido area, in the Las Chinas valley 3,000 km (1,800 miles) south of Santiago, stretches for 15 kilometers. Various rock outcrops contain numerous fossils.

The finds there allowed the scientists to surmise that present-day America and Antarctica were close to each other millions of years ago.

“There is strong evidence that there is a biogeographic link with other parts of the planet, in this case Antarctica and Australia, because we have two armored there closely related” to the Stegouros, said Soto.


Explore further

New dinosaur species from Chile had a unique slashing tail


More information:
Alexander Vargas, Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile, Nature (2021). DOI: 10.1038/s41586-021-04147-1. www.nature.com/articles/s41586-021-04147-1

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Dinosaur tail found in Chile stuns scientists (2021, December 4)
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Total solar eclipse brings darkness to Antarctic summer – CBC.ca

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Video released by NASA shows a total solar eclipse as seen from Western Antarctica on Saturday.

The Earth’s southernmost continent experiences continual daylight from mid-October until early April, but the eclipse brought a few minutes of total darkness.

NASA said the period of totality began at 2:44 a.m. ET. 

A solar eclipse occurs when the moon moves between the sun and Earth, casting a shadow on Earth, fully or partially blocking the sun’s light in some areas.

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For a total eclipse to take place the sun, moon, and Earth must be in a direct line. The only place that this total eclipse could be seen was Antarctica.

The eclipse was also expected to be visible partially from South Africa, Chile, New Zealand and Australia on Saturday.

North America gets its next glimpse of a full solar eclipse on April 8, 2024.

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