Superconductors are quantum materials that are perfect transmitters of electricity and electronic information. Although they form the technological basis of solid-state quantum computing, they are also its key limiting factor because conventional superconductors only work at temperatures near -270 °C. This has motivated a worldwide race to try to discover higher temperature superconductors. Materials containing CuO2 crystal layers (cuprates) are, at present, the best candidate for highest temperature superconductivity, operating at approximately -120 °C. But room temperature superconductivity in these compounds appears to be frustrated by the existence of a competing electronic phase, and focus has recently been on identifying and controlling that mysterious second phase.