Tiny loops measure the magnetic moment of electrons as it scans across a surface

While cephalopods are known to be intelligent it’s unlikely that any of them can detect a single electron. Until now, superconducting quantum interference devices, or Squids, haven’t been able to either, but Eli Seldov’s group report being able to do just that with them.

Squids use a superconducting loop to measure magnetic moments. As the loop interacts with a magnetic field, current is induced and measured. Smaller and smaller loops mean that smaller and smaller magnetic moments can be measured, but how small can a Squid get? By depositing superconducting films onto a sharp quartz pipette the team from the Weizmann Institute of Science in Israel made loops as small as 46nm in diameter, about the same size as a virus. The tips were then passed over a thin film of niobium to show they have the sensitivity and resolution necessary to measure the magnetic moment of a single electron.