This $300,000 project grant from the National Science Foundation's Engineering program (CFDA 47.041) will support research at the Trustees of the University of Pennsylvania to develop topologically protected gigahertz acoustic circuits. Over a three-year period ending in August 2025, the grantee will implement acoustic device analogues of topological electronic states operating in the gigahertz regime through theoretical analysis, simulation, fabrication, and nanoscale visualization. This is intended to realize acoustic devices with lower propagation loss than traditionally engineered circuits. The research is also expected to expedite prototyping of acoustic waveguides, delay lines, combiners, resonators and filters exploiting quantum valley Hall, quantum spin Hall and quantum Hall-like effects. Integrated education programs will train students in nanofabrication, microwave acoustic systems and scanning probe microscopy. Outreach to local students from underrepresented groups is also part of the effort.