Topological quantum state transfer beyond the single-excitation assumption

As is well known, within the single-excitation subspace, the Su-Schrieffer-Heeger (SSH) model exhibits a remarkable ability to transfer an excitation from one end of the lattice to the other. In this work, by relaxing the restriction of the single excitation, we find that a topological channel formed by the topological edge modes of the SSH model can also realize the transfer of arbitrary Gaussian states. Specifically, we investigate the state transfer process within a one-dimensional (1D) optomechanical lattice, which can be mapped to the SSH model with tunable coupling strength. By initially preparing the first optical mode in a squeezed vacuum state and adiabatically varying the system parameters over a full cycle, the squeezed vacuum state can be transferred to the $N\mathrm{th}$ mechanical mode. Furthermore, we extend our investigation to the transfer of arbitrary Gaussian states. Since Gaussian states can be described by the covariance matrix of the system, we reformulate the evolution equation of the covariance matrix in a Schr"odinger-type equation. This reformulation provides us with an intuitive way to show how an arbitrary Gaussian state is transferred. Our work broadens the application of topological systems for quantum state transfer, demonstrating that not only single-excitation states but also arbitrary Gaussian states, which include multiple excitations and quantum coherence, can be efficiently transferred, with potential implications for quantum information processing.