  Polar topologies, such as vortex and skyrmion, have attracted significant
interest due to their unique physical properties and promising applications in
high-density memory devices. Currently, most polar vortices are observed in
heterostructures containing ferroelectric materials and constrained by
substrates. In this study, we unravel arrays of polar vortices formed in
twisted freestanding bilayers composed of SrTiO3, a quantum-paraelectric
material. Depth-resolved structures of the bilayers are measured with
deep-sub-angstrom resolution and one picometer accuracy using multislice
ptychography, enabling identification of the three-dimensional variations of
polarization topology. Our findings reveal the evolution of the polar vortices
in the twisted overlapping layers, demonstrating the reverse of rotation manner
in the depth direction. Twisted freestanding bilayers provide a unique platform
for exploration and modulation of novel polar topologies.
