  The search for one-dimensional (1D) topologically-protected electronic states
has become an important research goal for condensed matter physics owing to
their potential use in spintronic devices or as a building block for
topologically non-trivial electronic states. Using low temperature scanning
tunneling microscopy, we demonstrate the formation of 1D electronic states at
twin boundaries at the surface of the noncentrosymmetric material BiPd. These
twin boundaries are topological defects which separate regions with
antiparallel orientations of the crystallographic \textit{b} axis. We
demonstrate that the formation of the 1D electronic states can be rationalized
by a change in effective mass of two-dimensional surface states across the twin
boundary. Our work therefore reveals a novel route towards designing 1D
electronic states with strong spin-orbit coupling.
