Electric<i>g</i>tensor control and spin echo of a hole-spin qubit in a quantum dot molecule

Abstract

The feasibility of high-fidelity single-qubit operations of a hole spin in a\nquantum dot molecule by electric g tensor control is demonstrated. Apart from a\nconstant external magnetic field the proposed scheme allows for an exclusively\nelectric control of the hole spin. Realistic electric gate bias profiles are\nidentified for various qubit operations using process-tomography-based optimal\ncontrol. They are shown to be remarkably robust against decoherence and\ndissipation arising from the interaction of the hole with host-lattice nuclear\nspins and phonons, with a fidelity loss of $\\approx$ 1 percent for gate\noperation times of $\\approx 10$ ns. Spin-echo experiments for the hole spin are\nmodeled to explore dephasing mechanisms and the role of pulse-timing\nimperfections on the gate fidelity loss is discussed.\n