Supercomputers in the USA, Europe, and Japan have proved indispensable for research into the effects of quantum mechanics at hugely different length scales. For example, at the Argonne Leadership Computing Facility (ALCF) in the USA, researchers from the University of Illinois at Urbana-Champaign (UIUC) are using Mira, a 10-petaflops IBM Blue Gene/Q supercomputer, to simulate the magnetism of iron selenide, a known high-temperature superconductor, at varying levels of pressure.