  We present new results on cavity-photon-assisted electron transport through
two lateral quantum dots embedded in a finite quantum wire. The double quantum
dot system is weakly connected to two leads and strongly coupled to a single
quantized photon cavity mode with initially two linearly polarized photons in
the cavity. Including the full electron-photon interaction, the transient
current controlled by a plunger-gate in the central system is studied by using
quantum master equation. Without a photon cavity, two resonant current peaks
are observed in the range selected for the plunger gate voltage: The ground
state peak, and the peak corresponding to the first-excited state. The current
in the ground state is higher than in the first-excited state due to their
different symmetry. In a photon cavity with the photon field polarized along or
perpendicular to the transport direction, two extra side peaks are found,
namely, photon-replica of the ground state and photon-replica of the
first-excited state. The side-peaks are caused by photon-assisted electron
transport, with multiphoton absorption processes for up to three photons during
an electron tunneling process. The inter-dot tunneling in the ground state can
be controlled by the photon cavity in the case of the photon field polarized
along the transport direction. The electron charge is delocalized from the dots
by the photon cavity. Furthermore, the current in the photon-induced side-peaks
can be strongly enhanced by increasing the electron-photon coupling strength
for the case of photons polarized along the transport direction.
