M. A. Eriksson

A quantum dot is a trap for electrons, just a few atoms in size, where a particle behaves like a ball in a tiny box. Place two such boxes side by side, and electrons can hop between them, making the system akin to a pair of communicating vessels.

Three guitar strings on the same instrument, but each tuning peg turns with a different resistance: one gives way immediately, another is stiff, and the third is completely stuck.