Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 72: Quantum dots: Transport properties

HL 72.1: Talk

Wednesday, April 2, 2014, 15:00–15:15, POT 251

Decoherence of an entangled states of a strongly-correlated double quantum dot structure through tunneling processes — •Carlos Alberto Büsser and Fabian Heidrich-Meisner — Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-University Munich, Germany

The entanglement of the spin state of two quantum dots is investigated out of equilibrium. First, we prepare a two-dot system in a perfect singlet state at time t=0. For t>0, one of the dots is tunnel-coupled to leads, including a finite voltage. Using the time-dependent density matrix renormalization group method, we study the time evolution of the spin correlations and the concurrence as a function of time since electrons hopping on and off the tunnel-coupled dot lead to decoherence. We observe that the spin correlation between the dots decays exponentially determining a decoherence rate. A similar rate can be defined for the concurrence. We study the dependence of these rates on voltage, tunnel coupling, and Coulomb repulsion and compare our numerical results to a master-equation approach derived for the weak-coupling limit.

This work was supported by the Deutsche Forschungsgemeinschaft (DFG) through FOR 912 under grant-no. HE5242/2-2.