Snowflake phononic topological insulator at the nanoscale

The authors propose here the first experimentally viable scheme of a topological insulator for sound waves at the nanoscale. This significantly advances the field of nanoscale phononics, adding helical waveguides to its toolbox. The proposed device could hardly be simpler as it relies purely on a geometrical design, based on the ``snowflake'' phononic crystal that has already been demonstrated experimentally.