Cuprate high-temperature superconductor. Illustration showing the two states of a cuprate high-temperature superconductor. The two electrons of a Cooper pair exist at relatively low energy and can carry current with no resistance. In this image, the superconducting Cooper-pair state is superimposed on a dashed pattern that indicates the static positions of electrons caught in a quantum 'traffic jam' at higher energy. At this higher energy, the material acts as a Mott-insulator incapable of carrying current.