A branch of physics based on quantum theory. The laws of classical physics do not hold at the scales of interest to nanotechnology. Thus, all the phenomena occurring on a scale of atoms must be described using formalism of quantum physics. The objects on a scale of nanometer do not behave as classical bodies which follow trajectories under influence of forces. Rather, they behave both as waves and rigid bodies, depending on a particular situation and a measurement one performs on them. This comes from the fact that in quantum theory energy can be emitted or absorbed by matter only in discrete units called quanta (singular quantum).

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