A team of scientists including researchers from the London Centre for Nanotechnology at UCL (University College London) and the IBM Almaden Research Centre has forged a breakthrough in understanding an intriguing phenomenon in fundamental physics: the Kondo effect. The findings are reported online today in the scientific journal Nature Physics. The Kondo effect, one of the few examples in physics where many particles collectively behave as one object (a single quantum-mechanical body), has intrigued scientists around the world for decades. When a single magnetic atom is located inside a metal, the free electrons of the metal screen the atom. That way, a cloud of many electrons around the atom becomes magnetised. Sometimes, if the metal is cooled down to very low temperatures, the atomic spin enters a so-called quantum superposition state. In this state its north-pole points in two opposite directions at the same time. As a result, the entire electron cloud around the spin will also be simultaneously magnetised in two directions.