Out-of-Time-Order Correlators in One-Dimensional XY model

Understand

Out-of-time-order correlators (OTOC) are considered to be a promising tool to characterize chaos in quantum systems.

• In this paper we study OTOC in XY model.
• With the presence of anisotropic parameter $\gamma$ and external magnetic field $\lambda$ in the Hamiltonian, we mainly focus on their influences on OTOC in thermodynamical limit.
• We find that the butterfly speed $v_B$ is dependent of these two parameters, and the recent conjectured universal form which characterizes the wavefront of chaos spreading are proved to be positive with varying $v_B$ in different phases of XY model.