We introduce a procedure to measure the density matrix of a material system
. The density matrix is addressed locally in this scheme by applying a sequ
ence of delayed-light pulses. The procedure is based on the stimulated Rama
n adiabatic passage technique. It is shown that a series of population meas
urements on the target state of the population transfer process yields unam
biguous information about the populations and coherences of the addressed s
tates, which, therefore, can be determined.