Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

Abstract

Physical systems exhibiting fast spontaneous chaotic oscillations are used to generate high-quality true random sequences in random number generators. The concept of using fast practical entropy sources to produce true random sequences is crucial to make storage and transfer of data more secure at very high speeds. While the first high-speed devices were chaotic semiconductor lasers, the discovery of spontaneous chaos in semiconductor superlattices at room temperature provides a valuable nanotechnology alternative. Spontaneous chaos was observed in 1996 experiments at temperatures below liquid nitrogen. Here we show spontaneous chaos at room temperature appears in idealized superlattices for voltage ranges where sharp transitions between different oscillation modes occur. Internal and external noises broaden these voltage ranges and enhance the sensitivity to initial conditions in the superlattice snail-shaped chaotic attractor thereby rendering spontaneous chaos more robust.

Intermittency route to chaos and broadband high-frequency generation in semiconductor superlattice coupled to external resonator

“…The latter makes the SL coupled to a resonator promising for using it as a key element in broadband sources of chaotic microwaves or fast random number generators [20,27,43,69], which could have applications in high-speed chaotic communications and spreadspectrum spectroscopy. In addition, previous works [24,28] have shown theoretically and experimentally that noise can significantly enhance the chaos generated in weakly coupled SLs. Taking into account these results we can assume that the inclusion of the noise in our model should lead to more developed chaos in charge dynamics in the SL under study and, thus, to the increase of bandwidth of microwave output.…”

Mechanism of resonant enhancement of electron drift in nanometer semiconductor superlattices subjected to electric and inclined magnetic fields

“…Fromhold et al 19 suggested that the dynamical origin of the resonant peaks lay in a delocalization of electrons through chaotic diffusion along the web. Note that chaos in SLs had been predicted since 1995, starting from the theoretical work of Bulashenko and Bonilla 81 , followed by many experimental and theoretical works (references to those before 2005 are given by Bonilla and Grahn 4 , while some more recent ones are given by Li et al 82 and by Alvaro et al 83 ). However they related to a different kind of chaos -spatiotemporal chaos that occurs in a different kind of SL -with a very large number of weakly interacting quantum wells subjected to dc and ac electric fields 4,81 .…”

Parameter dependence of high-frequency nonlinear oscillations and intrinsic chaos in short GaAs/(Al, Ga)As superlattices

“…To model the unavoidable fluctuations in the bias voltage, as well as the short-timescale processes in the electronic dynamics, stochastic terms [15] are introduced into equations (1)- (6). To account for the noise in the bias voltage, equation (2) is modified to…”