Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 19: Spin-controlled Transport I
HL 19.4: Vortrag
Dienstag, 23. März 2010, 10:15–10:30, H14
Spin-flip tunneling in quantum dots — •Lars Schreiber1, Floris Braakman1, Tristan Meunier1, Victor Calado1, Werner Wegscheider2, and Lieven Vandersypen1 — 1Kavli Institute of NanoScience, Delft, The Netherlands — 2Institute for Experimental and Applied Physics, University of Regensburg, Germany
Electron spins in a gate-defined double quantum dot formed in a GaAs/(Al,Ga)As 2DEG are promising candidates for quantum information processing as coherent single spin rotation and spin swap has been demonstrated recently. In this system we investigate the two-electron spin dynamics in the presence of microwaves (5..20 GHz) applied to one side gate. During microwave excitation we observe characteristic photon assisted tunneling (PAT) peaks at the (1,1) to (0,2) charge transition. Some of the PAT peaks are attributed to photon tunneling events between the singlet S(0,2) and the singlet S(1,1) states, a spin-conserving transition. Surprisingly, other PAT peaks stand out by their different external magnetic field dependence. They correspond to tunneling involving a spin-flip, from the (0,2) singlet to a (1,1) triplet. The full spectrum of the observed PAT lines is captured by simulations. This process offers novel possibilities for 2-electron spin manipulation and read-out.