Topological Phononic Logic

Topological metamaterials have protected dissipationless boundary modes engineered from their macroscopic arrangement, rather than their microscopic constituency. They can be designed by breaking either symmetry-enforced or accidental degeneracy in Dirac metamaterials. The latter case provides greater flexibility because a large number of tuning parameters can break the degeneracy to induce a topological phase. However, the design of a topological logic element, a switch that can be controlled by the output of a separate switch, remains elusive. Here we numerically demonstrate a topological phononic logic gate by exploiting the large phase space of accidental degeneracies in a honeycomb lattice. We find that a degeneracy can be broken by six physical parameters, and we tune these parameters to create a topological phononic switch that can be triggered by ultrasonic heating. Our design scheme is directly applicable to photonic crystals and may guide future designs of electronic topological transistors [1].
[1] Pirie, Sadhuka, Wang, & Hoffman, “Topological Phononic Logic”, arxiv:1809.09187