Parity effects in a Luttinger liquid: Diamagnetic and paramagnetic ground states

The concept of a Luttinger liquid in 1D is extended to include twisted boundary conditions on a ring and mesoscopic parity effects due to evenness and oddness of the particle number N0. Using Haldanes notion of topological excitations, a proof of Leggetts conjecture is presented, stating that the ground state of interacting 1D quantum systems is diamagnetic or paramagnetic depending on the parity of N0. The persistent currents produced by an Aharonov-Bohm flux are calculated and shown to have period and amplitude that are in agreement with recent experiments. © 1992 The American Physical Society.