Detection and manipulation of single Cr spin in a semiconductor quantum dot


Shinji Kuroda, Institute of Materials Science, University of Tsukuba

Recently, much effort has been devoted to manipulate a single spin in various systems aiming at applications for quantum computation. With the quantum dot containing a single atom of transition-metal element as a target of the single-spin system, we have been studying behaviors of the single magnetic spin in the dot in order to explore the method to control the single spin. Specifically, we have fabricated self-assembled CdTe dot containing a single Cr atom per dot by MBE and have investigated the Cr spin state by measuring the excitonic emission from the dot. As a result, we have revealed the energy diagram in which the Cr spin state is split according to the spin components due to the lattice distortion and the exchange interaction with an exciton. In addition, we have studied dynamics of the Cr spin by creating the specific component through the resonant excitation and by measuring the temporal evolution of the emission. The measurement of the relaxation process of the Cr spin state in the dark state without an exciton has revealed a long lifetime of the order of micro second, suggesting a possibility of quantum computing by using the single Cr spin as a quantum bit.
As a next step, we will proceed to manipulate the Cr spin state dynamically by surface acoustic wave (SAW) utilizing the strain-induced splitting of the Cr spin state.