Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 64: Quantum Information Systems: Mostly Concepts (jointly with HL)

TT 64.5: Talk

Wednesday, March 18, 2015, 12:00–12:15, EW 202

Electric dipole spin resonance in the presence of valley degeneracy — •Marko Rancic and Guido Burkard — University of Konstanz

We theoretically investigate the electric dipole spin resonance (EDSR) in a single Si/SiGe quantum dot in the presence of a magnetic field gradient, e.g., produced by a micomagnet. The control of electron spin states can be achieved by applying an oscillatory electric field, which induces periodic back and forth motion of the electron spin inside the quantum dot. This motion inside a magnetic field gradient, produces an effective periodic in-plane magnetic field, and allows for driven spin rotations near resonance. By solving a Lindblad master equation, we discuss possible electron spin relaxation and decoherence mechanisms relevant to EDSR. In Si there is 5% of naturally occurring nuclear spin 1/2 isotope, which causes the electron spin to decohere. Nuclear spins are included in our model through the additional random Overhauser magnetic field. Furthermore, a valley dependent g-factor, combined with intervalley scattering gives rise to another electron spin decoherence mechanism. The goal of our study is to describe the efficiency of a spin echo sequence in the presence of all mentioned relaxation and decoherence mechanisms.