  Multimode bulk acoustic systems show promise for use in superconducting
quantum computation. They can serve as a medium term memory storage, with
exceptional coherence times demonstrated, and they exhibit a mode density that
is physically highly compact. Here we experimentally demonstrate accessing
individual acoustic modes without being hindered by the uniform frequency
spacing of the modes. We use sideband control where a low-frequency modulation
is applied to the transmon qubit energy. The amplitude of the modulation
defines the qubit-acoustic mode coupling, and its frequency detunes the
acoustic sidebands, therefore enabling selectively switching on or off the
interaction, and allows for a full control on the individual modes.
