The world's weirdest trampoline doesn't bounce - it swings from side to side and even glides around corners. But no one can jump on it because it's less than a millimeter high.
Physicists develop nanoscale trampoline-like device that serves as breakthrough phonon waveguide
Imagine a trampoline so tiny, only 0.2 millimeters wide, with a surface thinner than anything you've ever seen, and a thickness of only about 20 millionths of a millimeter. It is filled with evenly spaced rounded triangular holes, giving it a unique perforated design. Despite its delicate appearance, this trampoline is nearly unstoppable. Once it starts moving, it loses almost no momentum and can keep swinging for a long time.
But it doesn’t just bounce up and down like a regular trampoline. Different areas of its surface move in different directions, including sideways. In the center, there's even a "trampoline within a trampoline," a smaller area where the action is even more frenzied. Here, the motion follows a precise triangular path, allowing the vibrations to perfectly round corners - a rarity in physics.
So what’s the point of designing a trampoline if no one can jump on it? Of course, this structure was not designed for humans. The people behind the trampoline - physicists from the University of Konstanz, the University of Copenhagen and ETH Zurich - hope to use it to demonstrate new methods of phonon transport.
The "trampoline" is actually a waveguide for phonons: a vibrating ultrathin film made of silicon nitride. Phonons can be said to be "sound quanta", the basic excited states on which solid crystal lattice vibrations are based. Physicists hope to use trampolines to demonstrate how phonons can be guided "around corners" with little loss of momentum through unique surface structures based on mathematical topological principles. This is important in circuits such as microchip circuits where signals need to be routed around edges and curves.
The results are impressive: using trampolines, the phonons can even move around sharp turns of 120 degrees with almost no loss of momentum. The number of phonons that "bounce" rather than curve around is less than one in 10,000. "This ultra-low loss is comparable to contemporary telecommunications equipment," says Konstanz physicist Oded Zilberberg.
Zilberberg is interested in studying these types of topological effects in surface structures and their applications. He believes that with this approach, it may be possible to construct complete "roads" for phonons. Zilberberg designed the exact structure of the trampoline. His colleagues from the University of Copenhagen and ETH Zurich then put the idea into practice. The research team's findings were recently published in the journal Nature.
But is it possible to build a trampoline for people to jump on? “I actually thought about it,” Zilberberg said with a laugh. "It would certainly be an interesting experiment. I imagine the principle would apply to larger-scale objects as well." Still, no one should try a "life-size" trampoline without a helmet.
Compiled from /scitechdaily