Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 32: Transport: Quantum Coherence and Quantum Information Systems - Part 2

TT 32.12: Talk

Thursday, March 30, 2006, 17:00–17:15, HSZ 304

Non-Markovian dynamics of double quantum dot charge qubits due to a phonon bath — •Jens Eckel, Stephan Weiss, and Michael Thorwart — Institut fuer Theoretische Physik IV, Universitaetsstrasse 1, 40225 Duesseldorf

We investigate the decoherent dynamics of charge qubits in two particular setups: (i) GaAs double quantum dots and (ii) two single P donor ions in a Si host lattice. In both cases, one excess electron is shared and a single charge qubit is formed. In particular, we study the charge qubit coupled to acoustic phonons which induce a non-Markovian dynamical behavior of the oscillations between the two charge states. Upon applying the numerically exact quasiadiabatic propagator path-integral scheme for both setups, the reduced density matrix is calculated, thereby avoiding the Born-Markov approximation. The damped coherent oscillations of the electron between the two dots determine a quality factor whose dependence on the lattice temperature, on the size of the quantum dots, as well as on the interdot coupling is studied systematically [1]. The comparison with the recent experimental result by Hayashi and coworkers [2] for double quantum dots will be discussed.

[1] M. Thorwart, J. Eckel and E. R. Mucciolo, Phys. Rev. B, in press.

[2] T. Hayashi et al., Phys. Rev. Lett. 91, 226804 (2003).