Researchers used polarized light to image electrons as a novel material transitioned between two different superconductive states. Photo by University of Tokyo
Nov. 6 (UPI) -- Under certain conditions, electricity can flow through a medium or circuit without any resistance. The phenomenon is called superconductivity, and it can happen several different ways.
Until now, scientists thought most of these different methods for inciting superconductivity were incompatible, but for the first time, researchers were able to combine two of these strategies. Scientists described the breakthrough in a new paper published Friday in the journal Science Advances.
The breakthrough involves what scientists call a Bose-Einstein condensate, or BEC, the fifth state of matter -- like plasma, but at the other end of the thermal spectrum.
"A BEC is a unique state of matter as it is not made from particles, but rather waves," Kozo Okazaki said in a news release.
"As they cool down to near absolute zero, the atoms of certain materials become smeared out over space. This smearing increases until the atoms -- now more like waves than particles -- overlap, becoming indistinguishable from one another," said Okazaki, an associate professor at the University of Tokyo's Institute for Solid State Physics.
BECs behave like a uniform material with entirely new properties, like superconductivity. Previously, BECs were only theoretical, but lab scientists were recently able to produce a superconducting BEC using a novel material derived from iron and selenium.
As mentioned, there are other methods for achieving superconductivity. When some materials are cooled to absolute zero, what's called a Bardeen-Cooper-Shrieffer regime, or BCS, is achieved. The material's atoms slow down and rigidly align, allowing electrons to pass seamlessly through the material.
Though both BEC and BCS regimes involve dramatically slowing a material's atoms by cooling materials to extremely frigid temperatures, the two regimes are distinct.
Scientists have previously hypothesized that by combining BEC and BCS states, researchers might be able to gain new insights into the phenomena of superconductivity.
"Demonstrating the superconductivity of BECs was a means to an end -- we were really hoping to explore the overlap between BECs and BCSs," said Okazaki. "It was extremely challenging but our unique apparatus and method of observation has verified it -- there is a smooth transition between these regimes. And this hints at a more general underlying theory behind superconduction. It is an exciting time to be working in this field."
Using an imaging technique called laser-based photoemission spectroscopy, Okazaki and his research partners were able monitor electron behavior as the novel material transitioned from BCS to BEC.
The experiments confirmed that electrons behaved differently during the two regimes -- differences that could ultimately yield insights into how superconductivity emerges as a material quality.
Superconductivity holds tremendous potential, but for now, the technology remains impractical.
But with each new insight into the mechanics of superconductivity, researchers hope to inch closer to the the construction of a superconductor that don't require extremely cold temperatures.
"With conclusive evidence of superconducting BECs, I think it will prompt other researchers to explore superconduction at higher and higher temperatures," said Okazaki. "It may sound like science fiction for now, but if superconduction can occur near room temperature, our ability to produce energy would greatly increase, and our energy needs would decrease."
