  Adaptive networks can sense and adjust to dynamic environments to optimize
their performance. Understanding their nanoscale responses to external stimuli
is essential for applications in nanodevices and neuromorphic computing.
However, it is challenging to image such responses on the nanoscale with
crystallographic sensitivity. Here, the evolution of nanodomain networks in
(PbTiO3)n/(SrTiO3)n superlattices was directly visualized in real space as the
system adapts to ultrafast repetitive optical excitations that emulate
controlled neural inputs. The adaptive response allows the system to explore a
wealth of metastable states that were previously inaccessible. Their
reconfiguration and competition were quantitatively measured by scanning x-ray
nanodiffraction as a function of the number of applied pulses, in which
crystallographic characteristics were quantitatively assessed by assorted
diffraction patterns using unsupervised machine-learning methods. The
corresponding domain boundaries and their connectivity were drastically altered
by light, holding promise for light-programmable nanocircuits in analogy to
neuroplasticity. Phase-field simulations elucidate that the reconfiguration of
the domain networks is a result of the interplay between photocarriers and
transient lattice temperature. The demonstrated optical control scheme and the
uncovered nanoscopic insights open opportunities for remote control of adaptive
nanoscale domain networks.
