How to build a quantum Newton's cradle

A quantum analogue of the popular "Newton's cradle" toy has been proposed by a duo of physicists in Italy. Like momentum transferred in the toy, the team argues that it should be possible to achieve the nearly perfect transmission of a quantum wavefunction along a line of ultracold atoms in a 1D Bose-Einstein condensate. According to the pair, the work could help develop quantum-information systems that achieve high-quality wave transmission. Best described as an "executive desk toy", a Newton's cradle is a device that demonstrates the conservation of energy and momentum. It consists of small, identically sized metal balls suspended from two horizontal bars. When a ball is lifted and allowed to fall, it strikes its immediate neighbour and comes to a stop. But its momentum is transferred across the rest of the spheres and propels only the sphere at the opposite end of the line into the air.