Dissipative Chaos in Semiconductor Superlattices

TL;DR

This paper investigates how nonlinear interactions between electrons and external fields in semiconductor superlattices can lead to dissipative chaos, with potential observability at terahertz frequencies using current laser technology.

Contribution

It introduces a semi-classical model incorporating dissipation and self-consistent fields to analyze chaotic dynamics in superlattices under terahertz excitation.

Findings

Chaotic regimes identified in amplitude-frequency space.

Chaos potentially observable with current terahertz laser sources.

Analogies drawn to Dicke model and Josephson junctions.

Abstract

We consider the motion of ballistic electrons in a miniband of a semiconductor superlattice (SSL) under the influence of an external, time-periodic electric field. We use the semi-classical balance-equation approach which incorporates elastic and inelastic scattering (as dissipation) and the self-consistent field generated by the electron motion. The coupling of electrons in the miniband to the self-consistent field produces a cooperative nonlinear oscillatory mode which, when interacting with the oscillatory external field and the intrinsic Bloch-type oscillatory mode, can lead to complicated dynamics, including dissipative chaos. For a range of values of the dissipation parameters we determine the regions in the amplitude-frequency plane of the external field in which chaos can occur. Our results suggest that for terahertz external fields of the amplitudes achieved by present-day free electron lasers, chaos may be observable in SSLs. We clarify the nature of this novel nonlinear dynamics in the superlattice-external field system by exploring analogies to the Dicke model of an ensemble of two-level atoms coupled with a resonant cavity field and to Josephson junctions.