A Spiral Surface Acoustic Wave Transducer for Quantum Information Processing

A superconducting surface acoustic wave transducer with a spiral geometry is proposed. This transducer is particularly useful for quantum information processing at cryogenic temperatures. Compared to an interdigital transducer, which launches acoustic waves in two directions, a spiral transducer (SPT) is capable of launching waves in four directions. This property allows to utilize the substrate surface in a more efficient way due to the transition from a line to a surface. Most importantly this kind of transducer gives us new possibilities for quantum information processing, since it can be used as a superconducting transmon qubit, which can be simultaneously coupled to two acoustic cavities. Moreover, it can be used for acoustic transport of quantum dot qubits, which could improve the means for long-range coupling of the qubits. The SPT has been simulated using COMSOL simulator, and it is also modeled using P-matrix and delta function model.