  The modification of initially entangled light pulses passing through
dispersive and absorbing four-port devices is studied, using recently obtained
results on quantum state transformations [Phys. Rev. A 59, 4716 (1999)]. The
fidelity and indices of quantum correlations based on the von Neumann entropy
are calculated. Their dependence on both the pulse shape and the four-port
device parameters is studied. It is shown, that due to dispersion and
absorption the quantum correlations are reduced substantially for large initial
entanglement.
