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Scientists unravel noise amplification in systems with memory



AMOLF scientists reveal noise amplification in memory systems

Two panes of glass with oil droplets between non-linear light channels. which observed random reflections By adjusting its position on one of the mirrors, the laser light (approaching from the left) becomes the signal (right). The appropriate amount of noise amplifies this signal when the random reflection conditions are met. Credit: Henk-Jan Boluijt. (AMOLF)

The signal can be amplified with the right amount of noise. But random resonance is a fragile phenomenon. Researchers at AMOLF are the first to investigate the role of memory for this phenomenon in small, fuel-filled optical cavities. The effect of slow nonlinearity (eg memory) on resonance sampling has never been considered. But these experiments suggest that random resonance is stronger against variations in signal frequency when the system has memory. This has implications in many areas of physics and energy technology. Especially Numerical scientists have shown that introducing a slow nonlinearity in a mechanical oscillator that harvests sound energy can increase the efficiency tenfold. They published their findings in the physical review letter on May 27

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7;s not easy to focus on a difficult task when two people are talking loudly next to you. However, complete silence is often not the best option. whether it is soft music long distance traffic noise or the conversation of people at a distance. For many people, the right amount of noise can help them concentrate better. “This is the human equivalent of resonance sampling,” said AMOLF group leader Rodriguez. Sampling takes place in a bistable nonlinear system, meaning that for a given input The output can be switched between two possible values. when the input is a periodic signal non-linear system response It can be amplified at the optimum volume of sound using random resonance conditions.”

ice age

In the 1980s, random resonances were proposed as an explanation for ice age recurrences. Since then It has been observed in many natural and technological systems. But this widespread observation poses a mystery to scientists. said Rodriguez. “Theories suggest that stochastic resonance can only occur at specific signal frequencies. However, many sound-enhancing systems exist in environments where signal frequencies fluctuate. Species eat plankton by detecting the signals they emit. And the right amount of noise will enhance the fish’s ability to detect that signal through the phenomenon of stochastic resonance, but this effect will survive the fluctuations in signal frequency occurring in such a complex environment. how?”

memory effect

Rodriguez and his Ph.D. student Kevin Peters, the first author of the paper, are the first to show that the impact of memory must be taken into account to solve this puzzle. “Random resonance theory assumes that nonlinear systems respond immediately to the input signal. Most systems respond to their surroundings with lag. and the response depends on what happened before,” he said. Such memory effects are difficult to theoretically explain and control in experiments. But the interaction photon group at AMOLF has managed to do both.

Rodriguez said: “We added a controlled amount of noise to the laser beam and directed it to a small channel. full of oil which is a non-linear system Light causes the temperature of the oil to rise and its optical properties to change, but not immediately. It takes about 10 microseconds, so the system isn’t instantaneous either. In our experiments, we have shown for the first time that random resonance can occur over a wide range of signals. frequency when there is a memory effect.”

energy harvesting

The researchers hope that the results will inspire colleagues in many other scientific fields to explore the effects of memory on their own systems. Rodriguez and his team examined the theoretical effects of asynchronous responses to mechanisms for energy harvesting to amplify the impact of these findings. “Small piezoelectric devices that harvest energy from vibrations are useful when batteries are difficult to replace, such as in pacemakers or other biomedical devices,” he explains. As far as can be harvested from environmental vibrations. If the memory effect is included”

The obvious next step for this group is to expand the system with multiple connected fuel inlets. and examine the overall behavior caused by noise. Rodriguez isn’t afraid to step out of his scientific comfort zone. He said: “It would be nice if we could team up with researchers who specialize in mechanical oscillators. If we can apply our memory effect to those systems. The impact on energy technology will be enormous.”



More information:
KJH Peters, Z. Geng, K. Malmir, JM Smith and SRK Rodriguez, Broadband Stochastic Resonance of Light and Enhanced Energy Harvesting 3 enabled by memory effects in nonlinear responses, physical review letter, 126, 213901 (2021). dx.doi.org/10.1103/PhysRevLett.126.213901

Reference: Scientists unravel noise amplification in memory systems (2021, 27 May). Retrieved 28 May 2021 from https://phys.org/news/2021-05-scientists-unravel-. noise-assisted-amplification-memory.html

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