Density-matrix approach to coherent transport and the measurement   problem
  Bloch-type equations for description of coherent transport in mesoscopic systems are applied for a study of the continuous measurement process. Both the detector and the measured system are described quantum mechanically. It is shown that the Schr\"odinger evolution of the entire system cannot be accommodated with the measurement collapse. The latter leads to quantum jumps which can be experimentally detected. 
S.A. Gurvitz