A GLOBAL QUANTUM MONTE-CARLO APPROACH FOR THE PERSISTENT CURRENT IN AN AHARONOV-BOHM RING WITH INTERACTING ELECTRONS

We propose a quantum Monte Carlo approach for the study of the thermo- equilibrium persistent current in an Aharonov-Bohm ring with interacti ng electrons. From topological considerations we derive a formula for the current, which leads to a global quantum Monte Carlo algorithm to evaluate the global current-phase relation at a given temperature with out going into simulations point-by-point in the phase. Notable featur es in the present approach are: (i) the problem of complex elements in the representation of the partition function is well-handled, (ii) be ing robust against possible randomness in the Hamiltonian, the basic f ormula captures all phase-dependent physics and hence makes the simula tion itself extremely efficient and reliable.