Nonequilibrium Hole Dynamics in Antiferromagnets: Damped Strings and Polarons br

We develop a nonperturbative theory for hole dynamics in antiferromagnetic spin lattices, as describedby thet-Jmodel. This is achieved by generalizing the self-consistent Born approximation to non-equilibrium systems, making it possible to calculate the full time-dependent many-body wave function.Our approach reveals three distinct dynamical regimes, ultimately leading to the formation of magneticpolarons. Following the initial ballistic stage of the hole dynamics, coherent formation of string excitationsgives rise to characteristic oscillations in the hole density. Their damping eventually leaves behind magneticpolarons that undergo ballistic motion with a greatly reduced velocity. The developed theory provides arigorous framework for understanding nonequilibrium physics of defects in quantum magnets andquantitatively explains recent observations from cold-atom quantum simulations in the strong couplingregime