  New features of molecular wires can be observed when they are irradiated by
laser fields. These effects can be achieved by periodically oscillating fields
but also by short laser pulses. The theoretical foundation used for these
investigations is a density matrix formalism where the full system is
partitioned into a relevant part and a thermal fermionic bath. The derivation
of a quantum master equation, either based on a time-convolutionless or
time-convolution projection-operator approach, incorporates the interaction
with time-dependent laser fields non-perturbatively and is valid at low
temperatures for weak system-bath coupling. From the population dynamics the
electrical current through the molecular wire is determined. This theory
including further extensions is used for the determination of electron
transport through molecular wires. As examples, we show computations of
coherent destruction of tunneling in asymmetric periodically driven quantum
systems, alternating currents and the suppression of the directed current by
using a short laser pulse.
