Tunneling in Double-Layer Optical Waveguides as Quantum Walks on Graphs

Modern integrated photonic quantum technologies are based on optical waveguides. The propagation of light in optical waveguides allows one to implement quantum computation and bosonic quantum simulation. Nevertheless, to further develop photonic quantum devices, one needs a precise mathematical description of quantum dynamics in waveguides. In this paper, we consider a double-layer array of optical waveguides and find exact analytical expressions for the Hamiltonian of the system and its parameters. The results are obtained both in the ideal waveguide approximation and in the case of photon loss in the waveguides.