Measurement induced dephasing and suppression of persistent current in a lattice ring

We investigate the effect of measurement on the persistent current density in a mesoscopic lattice ring with a threading Aharonov-Bohm flux. A quantum dot coupled with the ring is continuously monitored by a point contact detector. It is demonstrated by explicit analysis of the time-evolution of current density that the persistent current in the lattice ring can be suppressed completely due to the effect of detector implying the dephasing of quantum states. Practical experiments to observe the measurement induced dephasing is proposed.