  In theory ratchets enable energy harvesting by rectifying electrical
fluctuations in conductors and semiconductors. Certain rectification effects in
nanostructures have been demonstrated earlier. But these were not found to be
usable for energy harvesting, as they were not accomplished by asymmetric
transmission probabilities in the nanochannels, but rather by other secondary
effects. We propose and experimentally prove a nano-ratchet effect directly
linked to an asymmetry in the equilibrium transmission probability, which
becomes possible when a magnetic field is present. Remarkably, the
current/voltage do not disappear even without any intentional external
excitation. The rectification is manifested to be highly efficient to the
extent that generation of energy out of environmental electrical noises is
achieved.
