  The theory of exciton coupling to photons and LO phonons in quantum dots
(QDs) and quantum-dot molecules (QDMs) is presented. Resonant-round trips of
the exciton between the ground (bright) and excited (dark or bright) states
mediated by the LO-phonon alter the decay time and yield the Rabi oscillation.
The initial distributions of the population in the ground and the excited
states dominate the oscillating amplitude and frequency. This property provides
a detectable signature to the information stored in a qubit made from QD or QDM
for a wide range of temperature T. Our results presented herein provide an
explanation to the anomaly on T-dependent decay in self-assembled InGaAs/GaAs
QDMs recently reported by experiment.
