Cuprates, copper-based materials found in the late 1980s, superconduct at temperatures you can reach with cheap liquid nitrogen. Almost 40 years later, physicists still argue about why. Ars Technica covers a new Science study that got closer by listening.
The pseudogap
Above their superconducting temperature, cuprates seem to lose electrons at the energies where they should be. That’s the pseudogap. One camp says the electrons freeze into patterns like charge density waves. The other says they’re already forming Cooper pairs, the pairs that carry current in a superconductor, before the material can superconduct.
How they tested it
A team led by Milan Allan (LMU Munich) and Ingmar Swart (Utrecht) listened to shot noise, the tiny fluctuations from individual charges arriving in a current. Pairs carry twice the charge, so they make more noise, “like rain drumming on the roof” with heavier drops. Using a scanning tunneling microscope on BSCCO crystals, they tuned the energy they listened at like a radio dial. Pairing showed up right at the pseudogap energy, not just at the superconducting one, which points to the pairing camp.
My take
Using noise as the signal is a very hacker move. Room-temperature superconductors would change power grids and computing, so every step toward understanding these materials counts.
God Bless, and Happy hacking!
