  Levitated nanoparticles in vacuum are prime candidates for generating
macroscopic quantum superposition states of massive objects. Most protocols for
preparing these states necessitate coherent expansion beyond the scale of the
zero-point motion to produce sufficiently delocalized and pure phase-space
distributions. Here, we spatially expand and subsequently recontract the
thermal state of a levitated nanoparticle by modifying the stiffness of the
trap holding the particle. We achieve state-expansion factors of 25 in standard
deviation for a particle initially feedback-cooled to a center-of-mass thermal
state of \SI{155}{\milli\kelvin}. Our method relies on a hybrid scheme
combining an optical trap, for cooling and measuring the particle's motion,
with a Paul trap for expanding its state. Consequently, state expansion occurs
devoid of measurement backaction from photon recoil, making this approach
suitable for coherent wavefunction expansion in future experiments.
