Decoherence channels in the optical manipulation of charge and spin qubits in quantum dots – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2009 > Decoherence channels i...

Decoherence channels in the optical manipulation of charge and spin qubits in quantum dots

Optically driven spin control schemes in quantum dot systems exploiting spin dependent charge evolution are considered as promising candidates for quantum computers.

We show that even in the absence of direct spin-reservoir coupling, the spin state of a confined carrier in a quantum dot can undergo dephasing. The indirect dephasing process is studied in detail for specific optical spin control protocols using off- resonant trion excitations in doped semiconductor quantum dots. The microscopic description of the interaction between charges and their phonon reservoir is presented together with its non-Markovian nature.

Moreover, the decoherence channels resulting from radiative decay of the trion and imperfections of an adiabatic evolution are discussed. The parameters which allow for coherent control of the spin with a single qubit gate error as low as 10^-4 are indicated.