  We analyze theoretically the charging current into, and the transport current
through, a nanoscale two-dimensional electron system with two parallel quantum
dots embedded in a short wire placed in a photon cavity. A plunger gate is used
to place specific many-body states of the interacting system in the bias window
defined by the external leads. We show how the transport phenomena active in
the many-level complex central system strongly depend on the gate voltage. We
identify a resonant transport through the central system as the two spin
components of the one-electron ground state are in the bias window. This
resonant transport through the lowest energy electron states seems to a large
extent independent of the detuned photon field when judged from the transport
current. This could be expected in the small bias regime, but an observation of
the occupancy of the states of the system reveals that this picture is not
entirely true. The current does not reflect slower photon-active internal
transitions bringing the system into the steady state. The number of initially
present photons determines when the system reaches the real steady state. With
two-electron states in the bias window we observe a more complex situation with
intermediate radiative and nonradiative relaxation channels leading to a steady
state with a weak nonresonant current caused by inelastic tunneling through the
two-electron ground state of the system. The presence of the radiative channels
makes this phenomena dependent on the number of photons initially in the
cavity.
