Modulation of topological phase transition and topological quantum state of magnon-photon in one-dimensional coupled cavity lattices

Abstract

We propose a theoretical scheme to study the topological properties of magnon-photon in a one-dimensional coupled cavity lattice. Each unit cell is composed of the cavity microwave photon and the magnon, where the magnon is placed inside the cavity. The coupling of cavity microwave photon and magnon is controlled by an external magnetic field, and multiple cavities are coupled with each other to form a one-dimensional coupled cavity lattice system. Here, we study the topological phase transition and topological quantum channels of magnon-photon in the system by adjusting the magnon-photon coupling. Firstly, considering odd and even number lattices, we analyze and discuss the energy spectrum and the edge state in one-dimensional coupled cavity lattices. It is found that the energy band of the system is symmetric, and the edge states in the energy gap have time reversal symmetry, which makes the system topologically protected. At the same time, it is also noted that the maximum value, flipping, and period of the energy spectrum have changed, and the region of the edge state has expanded and extended. In addition, the edge state distribution can undergo the flipping process, which can achieve multi-channel topological quantum state transmission. Besides, considering the presence of defects and disorder in the system, it is found that when the random defect potential is small, the edge state of the system is robust to it, but when the random defect potential is large, the fluctuation of the energy band will be enhanced, and the edge state will be submerged in the energy band. However, when the disorder is very small, it can cause band fluctuations and flipping phenomena, and the edge state is robust to it, indicating the topological protection of the edge state. This work offers an effective way to study topological magnon-photon, which will have promising applications in quantum information processing.