Bloch oscillation is a phenomenon from solid state physics. It describes the oscillation of a particle (e.g. an electron) confined in a periodic potential when a constant force is acting on it. It was first pointed out by Bloch and Zener while studying the electrical properties of crystals. In particular, they predicted that the motion of electrons in a perfect crystal under the action of a constant electric field would be oscillatory instead of uniform. While in natural crystals this phenomenon is extremely hard to observe due to the scattering of electrons by lattice defects, it has been observed in semiconductor superlattices and in different physical systems such as cold atoms in an optical potential and ultrasmall Josephson junctions.
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Derivation
The one-dimensional equation of motion for an electron in a constant electric field E is:
which has the solution
The velocity v of the electron is given by
where
where a is the lattice parameter and A is a constant. Then v(k) is given by
and the electron position
This shows that the electron oscillates in real space. The angular frequency of the oscillations is given by
Discovery and experimental realizations
Bloch oscillations were predicted by Nobel laureate Leo Esaki in 1970. However, they were not experimentally observed for long as in natural solid state bodies