  The ability to engineer and manipulate different types of quantum mechanical
objects allows us to take advantage of their unique properties and create
useful hybrid technologies. Thus far, complex quantum states and exquisite
quantum control have been demonstrated in systems ranging from trapped ions to
superconducting resonators. Recently, there have been many efforts to extend
these demonstrations to the motion of complex, macroscopic objects. These
mechanical objects have important applications as quantum memories or
transducers for measuring and connecting different types of quantum systems. In
particular, there have been a few experiments that couple motion to nonlinear
quantum objects such as superconducting qubits. This opens up the possibility
of creating, storing, and manipulating non-Gaussian quantum states in
mechanical degrees of freedom. However, before sophisticated quantum control of
mechanical motion can be achieved, we must realize systems with long coherence
times while maintaining a sufficient interaction strength. These systems should
be implemented in a simple and robust manner that allows for increasing
complexity and scalability in the future. Here we experimentally demonstrate a
high frequency bulk acoustic wave resonator that is strongly coupled to a
superconducting qubit using piezoelectric transduction. In contrast to previous
experiments with qubit-mechanical systems, our device requires only simple
fabrication methods, extends coherence times to many microseconds, and provides
controllable access to a multitude of phonon modes. We use this system to
demonstrate basic quantum operations on the coupled qubit-phonon system.
Straightforward improvements to the current device will allow for advanced
protocols analogous to what has been shown in optical and microwave resonators,
resulting in a novel resource for implementing hybrid quantum technologies.
