Interaction-induced quantum dephasing in mesoscopic rings

Combining nonperturbative techniques with Monte Carlo simulations, we demonstrate that quantum coherence effects for a particle on a ring are suppressed beyond a finite length $L_{\varphi}$ even at zero temperature if the particle is coupled to a diffusive electron gas by means of long-range Coulomb interaction. This length is consistent with $L_{\varphi}$ derived from a weak-localization–type analysis.