# Dresden 2014 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 72: Quantum dots: Transport properties

### HL 72.1: Vortrag

### Mittwoch, 2. April 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.