Quantum memory unit with high-Q nanomechanical resonator

Hybrid quantum systems integrating mechanical resonators with superconducting qubits are promising quantum information platforms. Mechanical modes with high quality factor and small mode volume will serve as a great quantum memory unit to store qubit information with the advantage of long lifetime and small size. We present phononic crystal quartz resonators and surface acoustic wave quartz resonators with mechanical modes of high quality factor and small mode volume. The modes of both mechanical resonators are around 200MHz and will parametrically couple to GHz-frequency superconducting qubits with the assistance of a nonlinear circuit element (SNAIL) to mediate their frequency mismatch, based on three-wave mixing mechanics. The quartz resonators and SNAIL are on different chips which will be bonded in a flip-chip method and coupled via piezoelectric effect. Such modularity will also improve the flexibility and scalability of the hybrid system integration.