Physicists from and Italy have built an electrical circuit to simulate the dynamics of the interaction of photons. Developed by scientists scheme allowed to model the topological edge States of two entangled photons. The work presented in the journal Nature Communications.

In recent decades, scientists are actively studying topological effects in physics. For example, photonic topological States can help in the creation of topologically protected quantum computers. Such States have greater coherence, allowing physicists to better manage them. To date, the realization of photonic topological States is a challenging experimental task, however, theoretical studies show that the topological effects can be observed in the system of interacting photons.

Physicists from the University of ITMO, MIPT and the Polytechnic University of Torino considered a chain of nonlinear cavities, described by the model of the Bose — Hubbardin which photons can interact. The interaction of quantum particles gives rise to bound States of photons. However, the theory of Bose — Habbard not able to describe the appearance of coherent States, so physicists use a more complex model, which involves two processes: the tunneling of photons between the resonators, and the effective photon-Fatone interaction arising due to the nonlinearity of the medium. Under certain conditions, boundary coherent States of photons, called doubloons (doublones), can be described as a topological condition of light: the model presented by physicists, in the limit of strong interaction shifts in topological model SSH (Su-Schrieffer-Heeger).

However, creation of topological States of light, including doubloons, engineering is a difficult task, so scientists have developed an electrical circuit that effectively models the one-dimensional quantum problem.