Fig 1 (left) - this superconducting transistor-like device consists of several layers. It works as follows: Bound electron pairs in the first superconducting layer (S0) are broken apart by a voltage. Some of the single electrons (or quasiparticles as they are known in quantum parlance) tunnel into a second superconducting layer (S1). If this particle diffuses into a normal (nonsuperconducting) layer N, it can give up its energy to free electrons, which in turn can tunnel into a further superconducting layer (S2) where they constitute a current much amplified compared to the original input current.
Fig 2 (right) - schematic diagram showing the various parts of the superconductor transistor device.
Reported by: Pepe et al., Applied Physics Letters, 17 July 2000