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Ultralow loss phononic waveguides with topological protection

Xiang Xi (Niels Bohr Institute - University of Copenhagen)

Abstract Phononic devices, compared to electrical or photonic counterparts, feature slow propagation speed, strong confinement in materials and immunity to electromagnetic radiation. These properties are fuelling the prospect of chip-scale phononic circuits, which route, store and process classical or quantum information in more compact, efficient and robust ways. Over the past decade, a growing community of researchers has thus investigated and refined the properties of the elementary building block of this circuitry: a low-loss waveguide for phonons. Here I will present our recent results on realizing topological phononic waveguides with loss due to dissipation down to 3 dB/km, achieved by employing state-of-the-art dissipation dilution technique. The low loss also enables precise quantification of the backscattering immunity for topological transport, which is down to 1e-4 over 120-degree sharp bend. These results open opportunities for building a high-performance phononic circuits.