NCTS (South)


DATE2008-07-25

TIME13:30

PLACER203, 2F, NCTS, NCKU

FIELDQuantum Information Science

SPEAKER Prof. Ka-Di Zhu(朱卡的) - Department of Physics, Shanghai Jiao Tong University, China

TITLE Qubit Dynamics of Semiconductor Quantum Dots

ABSTRACTThe potential applications of semiconductor quantum dots confined in a microcavity in quantum information processing have generated considerable research efforts in recent years. In such a dot-cavity system, exciton in quantum dots constitutes an alternate two-level system instead of the usual two-level atomic system and the nanocavity with a small volume and high-Q is fabricated by micropillar, microdisk and photonic crystal slab. In the present talk, I shall demonstrate the qubit dynamics of quantum dots, especially the quantum dynamics of a strongly coupled single quantum dot-cavity system coupled a phonon bath in terms of a perturbation treatment based on a unitary transformation and an operator displacement. The decoherence induced by acoustic phonons as a function of the detuning between the cavity and exciton is obtained explicitly. It is shown that the detuning has a significant impact on the quantum dot exciton lifetime. For the experimental conditions, the larger the detuning, the longer the quantum dot exciton lifetime, which is in good agreement with the recent experimental observations [Hennessy et al., Nature 445, 896 (2007)].