Sublattice signatures of transitions in a PT -symmetric dimer lattice

Abstract

Lattice models with non-hermitian, parity and time-reversal (PTPT) symmetric Hamiltonians, realized most readily in coupled optical systems, have been intensely studied in the past few years. A PTPT-symmetric dimer lattice consists of dimers with intra-dimer coupling νν, inter-dimer coupling ν′ν′, and balanced gain and loss potentials ±iγ±iγ within each dimer. This model undergoes two independent transitions, namely a PTPT-breaking transition and a topological transition. We numerically and analytically investigate the signatures of these transitions in the time-evolution of states that are initially localized on the gain-site or the loss-site.