Superconductors, materials during which electricity flows with no resistance whatsoever might be extremely useful for future electronics. Now, engineers at the University of Tokyo have managed to make a superconductor out of a state of matter called a Bose-Einstein condensate (BEC) for the first time.
Sometimes called the fifth state of matter, behind the more commonly known as solids, gases & plasmas, Bose-Einstein condensates are what happens once you cool a gas of bosons right down to almost the coldest temperature possible. Experiments have shown that at this point, quantum phenomena are often observed at the macro scale. Scientists have used BECs as initial line to make exotic states of matter like supersolids, excitonium, quantum ball lightning & fluids exhibiting negative mass.
“A BEC is a unique state of matter because it isn’t made up of particles but rather waves”, says Kozo Okazaki, lead author of the study. “As they cool-down to near absolute zero, the atoms of certain materials become smeared out over space. This smearing increase until the atoms, now more like waves than particles overlap, becoming indistinguishable from each other. The resulting-matter behaves like it’s one single entity with new properties the preceding solid liquid or gas states lacked.”
In the new study, the Tokyo researchers have shown superconductivity in Bose-Einstein condensate, something that has never been verified in experiments before. The feat was achieved by making a BEC out of a cloud of iron & selenium atoms.
The key to discovery came from an overlap with an identical sort of matter called Bardeen Cooper Shrieffer (BCS) regime. Like BECs, BCS regimes are made by cooling clouds of atoms almost to absolute zero but the difference here is that, once they do, the atoms hamper & line up. It means that electrons can pass through them more easily enabling superconductivity.
The researchers on the new study were looking to ascertain what happens during the transition between a BCS & a BEC and if superconductivity was possible in BECs or whether it had been limited to BCSs. The team used photoemission spectroscopy to observe how electrons behaved in the 2 materials and surely saw that there was some superconductivity in BEC.
In practice, the discovery doesn’t have any direct applications for general public but deepening our understanding of the phenomenon can only help scientists make better superconductors in future. That successively could lead on to much faster & more efficient electronics.
“Demonstrating the superconductivity of BECs was means to an end. We were really hoping to explore the overlap between BECs and BCSs.” says Okazaki. “It was extremely challenging but our unique apparatus & method of observation has verified it, there’s a smooth transition between these regimes. And this hints at a more general underlying theory behind the super-conduction.”
The research was published in the journal Science Advances.