  Solid state spin qubits are promising candidates for quantum information
processing, but controlled interactions and entanglement in large, multi-qubit
systems are currently difficult to achieve. We describe a method for
programmable control of multi-qubit spin systems, in which individual
nitrogen-vacancy (NV) centers in diamond nanopillars are coupled to
magnetically functionalized silicon nitride mechanical resonators in a scanning
probe configuration. Qubits can be entangled via interactions with
nanomechanical resonators while programmable connectivity is realized via
mechanical transport of qubits in nanopillars. To demonstrate the feasibility
of this approach, we characterize both the mechanical properties and the
magnetic field gradients around the micromagnet placed on the nanobeam
resonator. Furthermore, we show coherent manipulation and mechanical transport
of a proximal spin qubit by utilizing nuclear spin memory, and use the NV
center to detect the time-varying magnetic field from the oscillating
micromagnet, extracting a spin-mechanical coupling of 7.7(9) Hz. With realistic
improvements the high-cooperativity regime can be reached, offering a new
avenue towards scalable quantum information processing with spin qubits.
