Discovery of new mechanisms to control the flow of sound

Using a network of vibrating nano-strings controlled with light, researchers from AMOLF have made sound waves move in a specific irreversible direction and attenuated or amplified the waves in a controlled manner for the first time. This gives rise to a lasing effect for sound. To their surprise, they discovered new mechanisms, so-called “geometric phases,” with which they can manipulate and transmit sound in systems where that was thought to be impossible. “This opens the way to new types of (meta)materials with properties that we do not yet know from existing materials,” says group leader Ewold Verhagen who, together with shared first authors Javier del Pino and Jesse Slim, publishes the surprising results on June 2 in Nature.