| The phenomenon of Bloch oscillation of charged carriers in periodic potentials is scientifically well established, yet the ancient notion that one can simply apply a voltage and extract oscillating voltage and current has escaped us. Here we review some experiments that graphically expose Bloch oscillation in semiconductor superlattices, describe a path to making a Bloch oscillator oscillate, compare a Bloch oscillator to quantum cascade laser and finally the current status of experiments to turn this rich science into a terahertz technology. |
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