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Dynamics, disorder effects, and PT-symmetry breaking in waveguide lattices with localized eigenstates

Recently, waveguide lattices with non-uniform tunneling amplitudes have been explored due to their myriad tunable properties, many of which arise from the extended nature of their eigenstates in the absence of disorder. Here, we investigate the dynamics, localization, and parity- and time-reversal-($\mP\mT$) symmetry breaking in lattices that support only localized eigenstates in the disorder-free limit. We propose three families of tunneling profiles that lead to qualitatively different single-particle time evolution, and show that the effects of weak disorder contain signatures of the localized or extended nature of clean-lattice eigenstates. We show that in lattices with localized eigenstates, the signatures of $\mP\mT$-symmetry breaking are acutely sensitive to the initial form of the wave packet. Our results suggest that waveguide lattices with localized eigenstates will exhibit a wide array of phenomena that are absent in traditional systems.