  The capability to temporarily arrest the propagation of optical signals is
one of the main challenges hampering the ever more widespread use of light in
rapid long-distance transmission as well as all-optical on-chip signal
processing or computations. To this end, flat-band structures are of particular
interest, since their hallmark compact eigenstates do not only allow for the
localization of wave packets, but importantly also protect their transverse
profile from deterioration without the need for additional diffraction
management. In this work, we experimentally demonstrate that, far from being a
nuisance to be compensated, judiciously tailored loss distributions can in fact
be the key ingredient in synthesizing such flat bands in non-Hermitian
environments. We probe their emergence in the vicinity of an exceptional point
and directly observe the associated compact localised modes that can be excited
at arbitrary positions of the periodic lattice.
