Coupling high-overtone bulk acoustic wave resonators via superconducting qubits

In this work, we present a device consisting of two coupled transmon qubits, each of which are coupled to an independent high-overtone bulk acoustic wave resonator (HBAR). Both HBAR resonators support a plethora of acoustic modes, which can couple to the qubit near resonantly. We first show qubit–qubit interaction in the multimode system and, finally, quantum state transfer where an excitation is swapped from an HBAR mode of one qubit to an HBAR mode of the other qubit.