Eigenmodes of Latent-Symmetric Quantum Photonic Networks

We investigate the impact of latent symmetries on the dynamics of photonic systems and their eigenmodes. Residing solely within the eigenspectral domain, latent symmetries are not visible in real space yet promise intriguing new ways to engineer the functionality of photonic systems. We study the eigenmodes of a 9-site latent-symmetric photonic network and experimentally demonstrate that classical antisymmetric excitations of the latent-symmetric sites are fundamentally precluded from populating so-called singlet sites. Since arbitrary extensions of the system at these sites do not break its latent symmetry, antisymmetric excitations cannot leave the initial system, which can be leveraged, e.g., for the storage of information. We expand this approach to multiparticle excitations and theoretically investigate how two-photon quantum excitations behave in our photonic network. We find that both latent symmetry and the presence of singlet sites are preserved in this realm. Overall, latent symmetries introduce a powerful new set of tools to the design of systems with desired functionality on any nanophotonic platform, paving the way for applications in photonic information processing.