The dynamics of charge qubit in a double quantum dot coupled to phonons is
investigated theoretically in terms of a perturbation treatment based on a
unitary transformation. The dynamical tunneling current is obtained explicitly.
The result is compared with the standard perturbation theory at Born-Markov
approximation. The decoherence induced by acoustic phonons is analyzed at
length. It is shown that the contribution from deformation potential coupling
is comparable to that from piezoelectric coupling in small dot size and large
tunneling rate case. A possible decoupling mechanism is predicted.Comment: 8 pages, 6 figure
Electromagnetically induced transparency (EIT) in quantum dot exciton systems in which the exciton behaves as a two-level system is investigated theoretically. It is shown that due to strong exciton–phonon coupling EIT can occur in such a quantum dot system and ultraslow light can propagate. The nonlinear optical absorption and Kerr coefficient based on EIT are also calculated. The numerical results show that giant nonlinear optical effects can be obtained while the frequency of the signal field differs only by an amount of LO phonon frequency from the exciton frequency in quantum dot systems.
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