Simulating graphene dynamics in synthetic space with photonic rings

Photonic honeycomb lattices have attracted broad interests for their fruitful ways in manipulating light, which yet hold difficulties in achieving arbitrary reconfigurability and hence flexible functionality due to fixed geometry configurations. Here we theoretically propose to construct the honeycomb lattice in a one-dimensional ring array under dynamic modulations, with an additional synthetic dimension created by connecting the frequency degree of freedom of light. Such a system is highly re-configurable with parameters flexibly controlled by external modulations. Therefore, various physical phenomena associated with graphene including Klein tunneling, valley-dependent edge states, effective magnetic field, as well as valley-dependent Lorentz force can be simulated in this lattice, which exhibits important potentials for manipulating photons in different ways. Our work unveils an alternative platform for constructing the honeycomb lattice in a synthetic space, which holds complex functionalities and could be important for optical signal processing as well as quantum simulation.