Demultiplexing infrasound phonons with tunable magnetic lattices

TL;DR

This paper demonstrates a novel, tunable magnetic lattice system that guides and sorts infrasound waves by frequency, enabling compact and reprogrammable manipulation of ultra-low frequency waves with minimal mass.

Contribution

It introduces the first experimental infrasound phonon demultiplexer using tunable magnetic lattices of meta-atoms, offering a lightweight and reprogrammable platform for ultra-low frequency wave control.

Findings

Successful demonstration of infrasound wave sorting by frequency

Tunable magnetic boundary controls wave propagation characteristics

Compact and low-mass platform for ultra-low frequency wave manipulation

Abstract

Controlling infrasound signals is crucial to many processes ranging from predicting atmospheric events and seismic activities to sensing nuclear detonations. These waves can be manipulated through phononic crystals and acoustic metamaterials. However, at such ultra-low frequencies, the size (usually on the order of meters) and the mass (usually on the order of many kilograms) of these materials can hinder its potential applications in the infrasonic domain. Here, we utilize tunable lattices of repelling magnets to guide and sort infrasound waves into different channels based on their frequencies. We construct our lattices by confining meta-atoms (free-floating macroscopic disks with embedded magnets) within a magnetic boundary. By changing the confining boundary, we control the meta-atoms' spacing and therefore the intensity of their coupling potentials and wave propagation characteristics. As a demonstration of principle, we present the first experimental realization of an infrasound phonon demultiplexer (i.e., guiding ultra-low frequency waves into different channels based on their frequencies). The realized platform can be utilized to manipulate ultra-low frequency waves, within a relatively small volume, while utilizing negligible mass. In addition, the self-assembly nature of the meta-atoms can be key in creating re-programmable materials with exceptional nonlinear properties.