We analyze the transport properties of a Luttinger liquid with an imbedded
impurity of explicitly time-dependent strength. We employ a radiative boundary
condition formalism to describe the coupling to the voltage sources. Assuming
the impurity time dependence to be oscillatory we present a full analytic
perturbative result in impurity strength for arbitrary interaction parameter
calculated with help of Coulomb gas expansion (CGE). Moreover, a full analytic
solution beyond the above restriction is possible for a special non-trivial
interaction strength which has been achieved independently by full resummation
of CGE series as well as via refermionization technique. The resulting
nonlinear current-voltage characteristic turns out to be very rich due to the
presence of the additional energy scale associated with the impurity
oscillation frequency. In accordance with the previous studies we also find an
enhancement of the linear conductance of the wire to values above the unitary
limit G0 = 2e2/h.Comment: 8 pages, 3 figures, submitted to PR