Control and manipulation of single electron spins in GaAs Quantum Dots

Full Text:We demonstrate coherent control of a quantum two-level system based on two electron spin states in a double quantum dot allowing state preparation, coherent manipulation, and projective read-out. These techniques are based on rapid electrical control of the exchange interaction. Separating and later recombining a singlet spin state provides a measurement of the spin dephasing time measured to be 10ns and is found to be limited by hyperfine interactions with the GaAs host nuclei. Rabi oscillations of two-electron spin states are demonstrated, and spin-echo pulse sequences are used to suppress hyperfine-induced dephasing. Using these quantum control techniques, a coherence time for two-electron spin states exceeding 1 micro second is observed