[1] Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA
[2] Tech Univ Munich, Walter Schottky Inst, Sch Nat Sci, Coulombwall 4, D-85748 Garching, Germany
[3] Tech Univ Munich, Walter Schottky Inst, MCQST, Coulombwall 4, D-85748 Garching, Germany
[4] Tech Univ Munich, Walter Schottky Inst, Sch Computat Informat & Technol, Coulombwall 4, D-85748 Garching, Germany
[5] Tech Univ Munich, Walter Schottky Inst, MCQST, Coulombwall 4, D-85748 Garching, Germany