  Hole spins in semiconductor quantum dots can be efficiently manipulated with
radio-frequency electric fields owing to the strong spin-orbit interactions in
the valence bands. Here we show that the motion of the dot in inhomogeneous
strain fields gives rise to linear Rashba spin-orbit interactions (with
spatially dependent spin-orbit lengths) and g-factor modulations that allow for
fast Rabi oscillations. Such inhomogeneous strains may build up spontaneously
due to process and cool down stress. We discuss spin qubits in Ge/GeSi
heterostructures as an illustration. We highlight that Rabi frequencies can be
enhanced by one order of magnitude by shear strain gradients as small as
$3\times 10^{-6}$ nm$^{-1}$ within the dots. This underlines that spin in
solids can be very sensitive to strains and opens the way for strain
engineering in hole spin devices for quantum information and spintronics.
