  Recent breakthrough on topological Anderson insulators revealed the breakdown
of the traditional perception that sufficiently strong disorder may induce the
appearance of topological protected transport states instead of destruction.
Although topological Anderson insulators have been observed in various
time-reversal symmetry breaking systems, the observation of topological
Anderson insulators protected by time-reversal symmetry remains scarce, which
are considered to be more promising in applications such as the integrated
devices. Here, we report the experimental observation of topological Anderson
insulator in a two-dimensional bilayer phononic crystal. The robust
spin-dependent edge states, as evidence of topological Anderson insulating
phase, are observed by introducing on-site disorder. In addition, spin Bott
index was computed to identify the topological invariants of the system with
disorder, which confirmed the occurrence of disorder-induced topological state.
Our results reveal that the impurities and defects introduced in the processing
of integrated devices may induce the formation of topological transport states,
which are promising for the exploration of new routes for the integration
devices design.
