  We predict a set of unusual quantum acoustic phenomena resulting from
sound-matter interactions in a fully tunable solid-state platform, in which an
array of solid-state spins in diamond are coupled to quantized acoustic waves
in a one-dimensional (1D) optomechanical crystal. We find that, by a spatially
varying laser drive that introduces a position-dependent phase in the
optomechanical interaction, the mechanical band structure can be tuned in situ,
consequently leading to unconventional quantum sound-matter interactions. We
show that quasi-chiral sound-matter interactions can occur, with tunable ranges
from bidirectional to quasi-unidirectional, when the spins are resonant with
the bands. When the solid-state spins'frequency lies within the acoustic
band-gap, we demonstrate the emergence of an exotic polariton bound state,
which can mediate long-range tunable, odd-neighbor and complex spin-spin
interactions. This work expands the present exploration of quantum phononics
and can have wide applications in quantum simulation and quantum information
processing.
