  Symmetry is one of the cornerstones of modern physics and has profound
implications in different areas. In symmetry-protected topological systems,
symmetries are responsible for protecting surface states, which are at the
heart of the fascinating properties exhibited by these materials. When the
symmetry protecting the edge mode is broken, the topological phase becomes
trivial. By engineering losses that break the symmetry protecting a topological
Hermitian phase, we show that a new genuinely non-Hermitian symmetry emerges,
which protects and selects one of the boundary modes: the topological monomode.
Moreover, the topology of the non-Hermitian system can be characterized by an
effective Hermitian Hamiltonian in a higher dimension. To corroborate the
theory, we experimentally investigated the non-Hermitian 1D and 2D SSH models
using photonic lattices and observed dynamically generated monomodes in both
cases. We classify the systems in terms of the (non-Hermitian) symmetries that
are present and calculate the corresponding topological invariants.
