半導体量子ホーレ素子における核スピン制御

摘要

For quantum information processing, it is essential to control quantum states without destroying their coherence. Nuclear spins are an ideal system for implementing quantum bits because they have an extremelylong coherence time. In this article, we review our recent experiments of the electrical control of nuclear spins in quantum Hall devices. The nuclear spins of the host semiconductor material are dynamically polarized through the hyperfine interaction between nuclear spins and electron spins in the breakdown regime of the quantum Hall effect. A pulsed radiofrequency magnetic field is applied using a built-in micrometal strip, which causes the nuclear-spin state to evolve coherently. Finally, the nuclear-spin state is read out by measuring the longitudinal resistance, which oscillates as a function of the pulse duration, i.e., a resistively detected Rabi oscillation.