  For quantum transport through mesoscopic system, a quantum master equation
approach is developed in terms of compact expressions for the transport current
and the reduced density matrix of the system. The present work is an extension
of Gurvitz's approach for quantum transport and quantum measurement, namely, to
finite temperature and arbitrary bias voltage. Our derivation starts from a
second-order cummulant expansion of the tunneling Hamiltonian, then follows
conditional average over the electrode reservoir states. As a consequence, in
the usual weak tunneling regime, the established formalism is applicable for a
wide range of transport problems. The validity of the formalism and its
convenience in application are well illustrated by a number of examples.
