0000000000178178

AUTHOR

Ryszard Gonczarek

showing 3 related works from this author

Spin-Based Quantum Information Processing in Magnetic Quantum Dots

2005

We define the qubit as a pair of singlet and triplet states of two electrons in a He-type quantum dot (QD) placed in a diluted magnetic semiconductor (DMS) medium. The molecular field is here essential as it removes the degeneracy of the triplet state and strongly enhances the Zeeman splitting. Methods of qubit rotation as well as two-qubit operations are suggested. The system of a QD in a DMS is described in a way which allows an analysis of the decoherence due to spin waves in the DMS subsystem.

Statistics and ProbabilityPhysicsStatistical and Nonlinear PhysicsQuantum PhysicsCondensed Matter::Mesoscopic Systems and Quantum Hall EffectPhase qubitCondensed Matter::Materials ScienceQuantum dotQuantum mechanicsQubitSinglet stateTriplet stateQuantum informationQuantum dissipationMathematical PhysicsSpin-½Open Systems & Information Dynamics
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Unavoidable decoherence in semiconductor quantum dots

2005

Phonon-induced unavoidable decoherence of orbital degrees of freedom in quantum dots is studied and the relevant time scales are estimated. Dephasing of excitons due to acoustic phonons and, in a polar medium, to optical phonons, including anharmonic effects and enhancement of the effective Fr\"ohlich constant due to localization, is assessed for typical self-assembled quantum dots. Temporal inefficiency of Pauli blocking due to lattice inertia is predicted. For quantum dots placed in a diluted magnetic semiconductor medium a magnon-induced dephasing of a spin is also estimated in accordance with experimental results.

PhysicsQuantum decoherenceCondensed matter physicsDephasingQuantum point contactCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsCondensed Matter::Materials Sciencesymbols.namesakePauli exclusion principleQuantum dot laserQuantum dotQuantum mechanicsPrincipal quantum numbersymbolsCondensed Matter::Strongly Correlated ElectronsQuantum dissipationPhysical Review B
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Dephasing of orbital and spin degrees of freedom in semiconductor quantum dots due to phonons and magnons

2006

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)

PhysicsQuantum decoherenceCondensed matter physicsCondensed Matter::OtherPhononExcitonMagnonDephasingMagnetic semiconductorCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter PhysicsCondensed Matter::Materials Sciencesymbols.namesakePauli exclusion principleQuantum dotsymbolsphysica status solidi c
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