Measurement of discrete charge in the systems of ultra-small tunnel junctions

The measurement of a charge of an almost isolated metal island gives discrete values. The non-equilibrium quantum effects on the shape of transition between these discrete values are studied here. They were shown to determine the width of transition in the limit of small temperatures and junction conductivities. Since any real measurement sets the system to non-equilibrium state the result of measurement is determined by properties of a measuring device. The most practical cases are discussed below: measurements by Fulton-Dolan electrometer as well as by co-tunneling electrometer and self-measurement of the charge by the SET transistor. The results obtained seem to be of general importance for non-equilibrium dissipative quantum dynamics.