EPJ B Highlight - When noise gets electrons moving

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Published on 02 December 2014

A new study demonstrates the existence of a counter-intuitive current, induced by the sound-based equivalent of a laser, with applications in novel microscopic semiconductor devices

Studying the motion of electrons in a disordered environment is no simple task, mainly because given the effect occurring at the scale of interest—referred to as quantum scale—these electrons are otherwise impossible to examine, due to the presence of incidental phenomena. Often, understanding such effects requires a quantum simulator designed to expose them in a different physical setup. This is precisely the approach adopted by Denis Makarov and Leonid Kon’kov from the Victor I. Il’ichev Pacific Oceanological Institute in Vladivostok in a new study published in EPJ B. They relied on a simulator of electronic motion subjected to noise stemming from a flux of sound waves. These findings could lead to semi-conductor devices of a new kind, operated through acoustic radiations.

This simulator is based on a theoretical model consisting of a disordered optical lattice—which was chosen to emulate the forces governing electronic charge transport that may be irregularly distributed in space. The lattice is then exposed to an additional optical lattice that is fluctuating and moving. This is a way of simulating sound waves generated by SASER, the sound-based analogue of a laser.

Through numerical simulation, the authors found that noise fluctuations lead to counter-intuitive electron transport behaviour and a change of direction in atomic transport. They deducted that being exposed to sound wave fluctuation gives rise to an electronic current that spontaneously changes its direction.

They elucidated this phenomenon using a theoretical model describing the evolution of atoms in what is referred to as momentum space. Specifically, they showed that the irregularity of the optical lattice plays only a minor role in the onset of such electronic current reversals. This suggests that the same effect can be observed in a regular optical lattice, with regularly spatially-distributed forces governing charge transport.

D. V. Makarov and L. E. Kon’kov (2014), Quantum transport in a driven disordered potential: onset of directed current and noise-induced current reversal, European Physical Journal B, DOI: 10.1140/epjb/e2014-50568-3