Topological excitations and bound photon pairs in a superconducting quantum metamaterial
Ilya S. Besedin, Maxim A. Gorlach, N. N. Abramov, Ivan Tsitsilin, Ilya N. Moskalenko, Alina A. Dobronosova, Dmitry O. Moskalev, Alexey R. Matanin, Nikita S. Smirnov, Ilya A. Rodionov, Alexander N. Poddubny, A. V. Ustinov
Abstract
Topological photonics enables resilient routing and localization of light. Of special interest are topological states of quantum light promising disorder-robust quantum correlations. Here, the authors design and fabricate a one-dimensional dimerized array of superconducting qubits. Performing microwave spectroscopy of this fabricated quantum metamaterial, they observe not only single-photon topological states but also the bands of exotic bound photon pairs mediated by the anharmonicity of qubits. They also discuss the two-photon bound edge-localized state and analyze the robustness of photon-photon correlations.