Researchers from the RIKEN Center for Emergent Matter Science have developed a device called a Josephson junction, which can efficiently split Cooper pairs as they move from a superconductor into two one-dimensional conventional conductors. The device has two aluminum electrodes and the electrodes are bridged by two semiconductor nanowires. Earlier, most studies of Cooper-pair splitting have been done using zero-dimensional ‘quantum dots’ combined by superconductors. The breakthrough indicates that the device could be used to produce what is known as a topological superconducting state, in which the superposition of an electron and a hole forms Majorana fermions, an unusual kind of particle that is equal to its own antiparticle.