Generation of chiral solitons in antiferromagnetic chains by a quantum quench

We analyze the time evolution of a magnetic excitation in a spin-1/2 antiferromagnetic Heisenberg chain after a quantum quench. By a proper modulation of the magnetic exchange coupling, we prepare a static soliton of total spin 1/2 as an initial spin state. Using bosonization and a numerical time dependent density matrix renormalization group algorithm, we show that the initial excitation evolves to a state composed of two counter-propagating chiral states, which interfere to yield <S^z> = 1/4 for each mode. We find that these dynamically generated states remain considerably stable as time evolution is carried out. We propose spin-Peierls materials and ultracold-atom systems as suitable experimental scenarios in which to conduct and observe this mechanism.