Semiclassical theory of front propagation and front equilibration following an inhomogeneous quantum quench

Understand

We use a semiclassical approach to study out of equilibrium dynamics and transport in quantum systems with massive quasiparticle excitations having internal quantum numbers.

• In the universal limit of low energy quasiparticles, the system is described in terms of a classical gas of colored hard-core particles.
• Starting from an inhomogeneous initial state, in this limit we give analytic expressions for the space and time dependent spin density and spin current profiles.
• Depending on the initial state, the spin transport is found to be ballistic or diffusive.