Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 17: Quantum Protocols and Gates SYQR 3 (with Q)

A 17.5: Talk

Tuesday, March 18, 2014, 11:30–11:45, Kinosaal

Strain-induced active tuning of the coherent tunneling in quantum dot molecules — •Eugenio Zallo¹, Rinaldo Trotta², Yongheng H. Huo¹, Paola Atkinson³, Fei Ding¹, Armando Rastelli², and Oliver G. Schmidt¹ — ¹Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany — ²Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria — ³Institut des NanoSciences des Paris, UPMC CNRS UMR 7588,4 Place Jussieu Boite courier 840, Paris 75252 Cedex 05, France

Quantum dot molecules (QDMs) are formed by orbital hybridization of wavefunctions in two closely positioned quantum dots (QDs), and they are important for a coherent manipulation of qubits in quantum information applications. The coupling strength is the key parameter determining the operation rate of quantum gates based on QDMs. Recently, ultrafast optical control of the entangled state of two electron spins interacting through tunneling in a QDM was demonstrated. Despite the extensive efforts in the community, it is a formidable task to actively tune the tunnel coupling in a single QDM obtained by vertical stacking of two semiconductor quantum dots. In this presentation, a novel class of devices that allow large strain and electric fields to be applied to single QD and QDM will be introduced first. Then, the experimental achievement of this active tuning will be demonstrated. By means of externally induced strain fields the coupling strength of holes confined in vertically coupled InGaAs/GaAs QDs was varied by more than 14%.