Paralysed by disorder

摘要

Those familiar with the game of pachinko -in which, in its simplest incarnation, little balls bounce and cascade chaotically through a regular lattice of pin-like obstacles -have some idea of what a current of electrons goes through when it flows through the ordered crystal lattice of a metallic wire. But now imagine that you are playing quantum pachinko. Instead of little balls, wavelets shoot around the atomic obstacle course. The rules of the game are suddenly very difficult: if the waves have the right energy, they complete the course with aplomb, moving around the lattice essentially unimpeded. But you only need to change things slightly, by putting the obstacles in a marginally more disordered arrangement, to stop those quantum waves in their tracks.