‘Strange Metals’ – Scientists Observe Quantum Entanglement In ‘Billions of Billions’ of Ytterbium Electrons

Friday, 17 January 2020 - 9:43AM
Friday, 17 January 2020 - 9:43AM
‘Strange Metals’ – Scientists Observe Quantum Entanglement In ‘Billions of Billions’ of Ytterbium Electrons
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Image Credit: IQOQI Innsbruck/Harald Ritsch
Quantum entanglement has been observed in "billions of billions" of electrons, according to a report from Science Daily. A paper was published in this week's issue of the peer-reviewed journal Science, which is out today.

Teams of physicists working at Rice University in the United States and the Vienna University of Technology in Austria were examining a compound of the metals ytterbium, rhodium (which is part of the platinum group of elements), and silicon (which is in everything from computer chips to the Earth's crust).

First, researchers created a microscopically thin film of this compound – YbRh2Si2 – and then chilled it to almost absolute zero: 1.4 Kelvin. "Absolute zero" is the lowest temperature known to be possible: 0 Kelvins, –273 degrees Celsius, or –459 degrees Fahrenheit.

Then, they shone a terahertz frequency of electromagnetic radiation on this film. At the same time, they systematically toggled this compound between the two different quantum phases that exist on either side of that temperature and observed how the atoms on the film reacted during the transition.

"With strange metals, there is an unusual connection between electrical resistance and temperature," explained Silke Bühler-Paschen, the study's co-author from Vienna University's TU Wien Institute for Solid State Physics, in a statement from Rice University. "This does not seem to be due to the thermal movement of the atoms, but to quantum fluctuations at the absolute zero temperature."

According to the statement from Rice, "The experiments revealed 'frequency over temperature scaling,' a telltale sign of quantum criticality."

Another study co-author, Qimiao Si – a professor of physics and astronomy at Rice University, added, "At a quantum critical point, things are so collective that we have this chance to see the effects of entanglement, even in a metallic film that contains billions of billions of quantum mechanical objects."

The experiment required a "painstaking" level of precision from the study's co-lead author, Xinwei Li, a postdoctoral physics researcher from the California Institute of Technology. Only a small fraction of the total teraherz signal could be transmitted, and the signal they were looking for was even fainter. It took hours to gather a single data point – and to gather enough of them to be confident in their discovery.

Despite the long hours and scrupulously detailed work, researchers focused instead on the goal that understanding how these kinds of quantum materials work can help drive futuristic leaps forward in communication and computer technologies.

"Quantum entanglement is the basis for storage and processing of quantum information," explained Si. "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."

Cover Image Credit: IQOQI Innsbruck/Harald Ritsch