  We analyze quantum state of fermionic carriers in a transport channel
attached to a particle reservoir. The analysis is done from the first
principles by considering microscopic models of the reservoir and transport
channel. In the case of infinite effective temperature of the reservoir we
demonstrate a full agreement between the results of straightforward numerical
simulations of the system dynamics and solution of the specified master
equation on the single-particle density matrix of the carriers in the channel.
This allows us to predict the quantum state of carriers in the case where
transport channel connects two reservoirs with different chemical potentials.
