Topological protection of highly entangled non-Gaussian two-photon states

We study theoretically the evolution of entangled non-Gaussian two-photon states in disordered topological lattices. Specifically, we consider spatially entangled two-photon states, modulated by Laguerre polynomials up to the 3rd order, which feature ring-shaped spatial and spectral correlation patterns. Such states are discrete analogs of photon-subtracted squeezed states, which are ubiquitous in optical quantum information processing or sensing applications. We find that, in general, a higher degree of entanglement coincides with a loss of topological protection against disorder, this is in line with previous results for Gaussian two-photon states. However, we identify a particular regime in the parameter space of the considered non-Gaussian states, where the situation is reversed and an increase of entanglement can be beneficial for the transport of two-photon quantum states through disordered regions.