One-way street for sound waves

Ten years ago, a team of researchers succeeded in suppressing the propagation of sound waves in the backward direction (external page link); however, this also attenuated the waves travelling forwards. As explained in the ETH News article of Oliver Morsch, we have now developed a concept for preventing sound waves from travelling backwards without deteriorating their propagation in the forward direction. In the future, this concept, which has recently been published in external page Nature Communications, could also be applied to electromagnetic waves.