Putting noise to work

September 28, 2018, Forschungsverbund Berlin e.V. (FVB)
Credit: CC0 Public Domain

Noise is often undesirable—for example, in a recorded conversation in a noisy room, in astronomical observations with large background signals, or in image processing. A research team from China, Spain and Germany has demonstrated that noise can induce spatial and temporal order in nonlinear systems. This effect may be used in the future to identify signals that are hidden in a large amount of noise. Inversely, signals may be embedded in a noisy background and thereby be ciphered in order to recover them later.

The results were published in two manuscripts published back-to-back in Physical Review Letters, one focusing on the experimental investigation, and the second one covering the theoretical investigation based on numerical simulations.

Noise sometimes plays a constructive role that can be exploited to produce useful results. Applying in combination with small-amplitude periodic oscillations to a nonlinear can result in very intricate effects. Noise can drive a stationary system into an oscillatory state with coherent current self-oscillations having tunable frequencies between zero and about 100 MHz, which is called a coherence resonance.

By adding to the noise small-amplitude periodic oscillations with a frequency close to that of the current self-oscillations, the nonlinear system can be phase locked to the coherence resonance, which is referred to as a stochastic resonance. This can be used as a passive lock-in amplifier, without a reference signal and with a much shorter integration time than available for conventional lock-in amplifiers. Until now, all methods detecting weak signals are actively based on the correlation with a known reference signal, and it is impossible to identify unknown signals hidden in a background with strong noise. Typical lock-in amplifiers need a reference signal in the tens of Hz to MHz range and integration times of the order of milliseconds. The wide frequency range of the coherence resonance allows for the operation without any reference signal and greatly reducing the integration time necessary to process the signal.

The research team has experimentally demonstrated the occurrence of coherence and stochastic resonances at room temperature in a doped, weakly coupled GaAs/(Al,Ga)As superlattice with 45 percent Al. Numerical simulations of the electron transport based on a discrete sequential tunneling model carried out simultaneously reproduce these results qualitatively very well. In addition, the theoretical model can be used to determine the device-dependent critical current for the directly from the experimental results.

Explore further: Why noise can enhance sensitivity to weak signals

More information: Emanuel Mompo et al, Coherence Resonance and Stochastic Resonance in an Excitable Semiconductor Superlattice, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.086805

Related Stories

Why noise can enhance sensitivity to weak signals

April 5, 2018

A team of Japanese researchers has discovered a new mechanism to explain stochastic resonance, in which sensitivity to weak signals is enhanced by noise. The finding is expected to help electronic devices become smaller and ...

Random noise helps make signals clearer

December 6, 2011

Scientists have shown the energy conditions, under which a weak signal supplied to a physical system emerges as a stronger signal at the output thanks to the presence of random noise (a process known as stochastic resonance), ...

Neuron circuit may enable pitch perception applications

August 19, 2014

The first FitzHugh-Nagumo neuron circuit designed to include noise and exhibit the Ghost Stochastic Resonance effect has been presented by researchers from Université de Bourgogne in France. Their circuit operates according ...

Recommended for you

Taking a close look at bacteria

October 23, 2018

Yong Wang, assistant professor of physics, and graduate student Asmaa Sadoon have been studying how molecules travel through bacterial cytoplasm in order to understand more about how these tiny organisms function. Using new ...

Researchers validate 80-year-old ferroelectric theory

October 23, 2018

Researchers have successfully demonstrated that hypothetical particles that were proposed by Franz Preisach in 1935 actually exist. In an article published in Nature Communications, scientists from the universities in Linköping ...

Understanding the building blocks for an electronic brain

October 22, 2018

Computer bits are binary, with a value of zero or one. By contrast, neurons in the brain can have many internal states, depending on the input that they receive. This allows the brain to process information in a more energy-efficient ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.