In low temperature superconductors, cooper pairs formation is thought to be responsible for the superconductivity of the material. Cooper pairs are electrons that overcome their repulsion and loosely pair up and behave like Bosons. Apparently cooper pairs will travel down a regular conducting wire for a little bit before seperating. The distance the pair can travel before seperating is called the Normal Metal Coherence Length. Some scientists took advantage of this property by getting the two electrons of a cooper pair to travel down different wires, where the two wires were close enough to keep the cooper pair intact. They then studied the properties of cooper pairs by varying the distance between the wires and measuring the resistance. Pretty cool stuff.
