Coexistence of stable and unstable population dynamics in a nonlinear non-Hermitian mechanical dimer
We experimentally and theoretically investigate the dynamics of Hatano-Nelson model on two sites (dimer), and then we make the non-reciprocal hoppings depend on the population imbalance between the two sites, thus introducing the non-Hermiticity in a dynamical manner. In the latter case we find that we can tune from stable to unstable population dynamics by simply changing the initial phase difference between the two sites.