0000000000132254
AUTHOR
Janusz Jacak
Quantum information processing on spin degrees of freedom in QDs placed in diluted magnetic semiconductor
The spin degrees of freedom in quantum dot (QD) embedded in a diluted magnetic semiconductor (DMS) medium are considered in a model of a qubit and a gate for quantum information processing (QIP). The qubit is defined as a singlet and triplet pair of states of two electrons in a He-type QD in the DMS medium with strongly enhanced gyromagnetic factor. Methods of qubit rotation (Rabi oscillations) as well as two-qubit operations are suggested and analyzed. Moreover, decoherence related to spin waves (magnon-induced dephasing) in this new system (QD in DMS) is studied, and the relevant time-scale is estimated in accordance with preliminary experimental results. (© 2006 WILEY-VCH Verlag GmbH & C…
Dephasing of orbital and spin degrees of freedom in semiconductor quantum dots due to phonons and magnons
Phonon-induced decoherence of orbital degrees of freedom in quantum dots (QDs) (GaAs/InAs) is studied and the relevant time-scales are estimated versus dot dimension. Dephasing of excitons due to acoustic phonons and optical phonons, including enhancement of the effective Frohlich constant caused by localization, is assessed for the state-of-art QDs. Temporal inefficiency of Pauli blocking in QDs due to lattice inertia is additionally predicted. For QD placed in a diluted magnetic semiconductor medium a magnon induced dephasing of spin is estimated in accordance with experimental results for Zn(Mn)Se/CdSe. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)