Excitonic wave-packet evolution in a two-orbital Hubbard model chain: A real-time real-space study

Motivated by experimental developments introducing the concept of spin-orbit separation, we study the time evolution of an excitonic wave-packet using a two-orbital Hubbard model. The excitonic wave-packet is created by exciting an electron from a lower energy half-filled orbital to an empty higher-energy orbital. We carry out the real-time dynamics of the resulting excitonic wave-packet, using the time-dependent density matrix renormalization group method. We find clear evidence of charge-spin and spin-orbit separation in real-space, by tracking the time evolution of local observables. We also provide the quantitative relation between Hund’s coupling and orbiton velocity, where we find that the orbiton velocity increases together with the Hund’s coupling. We also present a comparative study of hole (in one orbital) and exciton (in two orbitals) dynamics in one-dimensional systems. Moreover, we analyze the dynamics of excitonic wave-packet with spin-flip excitation.