State measurements with short laser pulses and lower-efficiency photon detectors

The use of a short probe laser pulse for state measurements of two-level systems has been proposed by Cook. In previous work we have investigated to what extent this proposal fulfills the projection postulate if ideal photon detectors are considered. For detectors with an overall efficiency of less than 1 complications arise for single systems, and for this case we present a simple criterion for a laser pulse to act as a state measurement and to cause an almost complete state reduction.