  Coherent tripartite interactions among degrees of freedom of completely
different nature are instrumental for quantum information and simulation
technologies, but they are generally difficult to realize and remain largely
unexplored. Here, we predict a tripartite coupling mechanism in a hybrid setup
comprising a single NV center and a micromagnet. We propose to realize direct
and strong tripartite interactions among single NV spins, magnons and phonons
via modulating the relative motion between the NV center and the micromagnet.
Specifically, by introducing a parametric drive (two-phonon drive) to modulate
the mechanical motion (such as the center-of-mass motion of a NV spin in
diamond trapped in an electrical trap or a levitated micromagnet in a magnetic
trap), we can obtain a tunable and strong spin-magnon-phonon coupling at the
single quantum level, with up to two orders of magnitude enhancement for the
tripartite coupling strength. This enables, for example, tripartite
entanglement among solid-state spins, magnons, and mechanical motions in
quantum spin-magnonics-mechanics with realistic experimental parameters. This
protocol can be readily implemented with the well-developed techniques in ion
traps or magnetic traps, and could pave the way for general applications in
quantum simulations and information processing based on directly and strongly
coupled tripartite systems.
