Non-Hermitian topological lattices

Non-Hermitian skin effect is a special localization phenomenon in periodic lattices with gain and loss: all the eigenstates of the finite system become localized at the edge. This is related to the nontrivial topological invariant -- nonzero winding number of the complex energy spectrum E(k) as a function of wave vector k. The effect is potentially useful for sensing applications.

We have recently predicted a peculiar type of non-Hermitian effect in arrays of atoms directionally coupled to the waveguide [1-2]. If atoms emit photons mostly to the right, single photons get localized at the right edge [3], but bound photon pairs get localized at the opposite left edge. This can be seen a special type of non-Hermitian skin effect in the interacting system.

We also work on other types of systems [4-6] where nonlinearity and interactions interplay with non-Hermiticity. One example is coupled laser arrays [6], we study them together with Nir Davidson's lab

Selected recent publications

  1. Jiaming Shi and Alexander N. Poddubny, Bound, antibound and resonance two-photon states in chiral waveguide QED, arXiv:2604.20602 (2026)
  2. Jiaming Shi and Alexander N. Poddubny, Chiral Dissociation of Bound Photon Pairs for a Non-Hermitian Skin Effect, Phys. Rev. Lett. 134, 233602 (2025)
  3. Alexander Poddubny, Janet Zhong, and Shanhui Fan, “Mesoscopic non-Hermitian skin effect”, Phys. Rev. A 109, L061501 (2024),
  4. Janet Zhong, Heming Wang, Alexander N Poddubny, Shanhui Fan, [Topological nature of edge states for one-dimensional systems without symmetry protection](https://doi.org/10.1103/k77w-ft26, Phys. Rev. Lett. 135, 016601 (2025)
  5. Alexander N. Poddubny, "Interaction-induced analog of a non-Hermitian skin effect in a lattice two-body problem", Phys. Rev. B 107, 045131 (2023)
  6. Konstantin Manannikov, Sagie Gadasi, Ekaterina Mironova, Eran Bernstein, Andrei Poliakov, Nir Davidson, Alexander N. Poddubny, "Klein tunneling of the laser coherence" arXiv:2605.22033 (2026)