Adiabatic transport properties of an exactly soluble one-dimensional quantum many-body problem.

We study an interacting one-dimensional quantum lattice gas, based on the Heisenberg-Ising ring. The particles are given a charge, and the ring is threaded by a magnetic flux. We then calculate exactly the energy of the state, which begins as the ground state with zero magnetic flux, when the magnetic flux is adiabatically increased. We find the result that the period of the ground state is two flux quanta, which can be interpreted as charge carriers with half-integer charge.