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تسجيل مستخدم جديدDirect measurement of the hole-nuclear spin interaction in single quantum dots
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We use photoluminescence spectroscopy of bright and dark exciton states in single InP/GaInP quantum dots to measure hyperfine interaction of the valence band hole with nuclear spins polarized along the sample growth axis. The ratio of the hyperfine constants for the hole (C) and electron (A) is found to be C/A~-0.11. In InP dots the contribution of spin 1/2 phosphorus nuclei to the hole-nuclear interaction is weak, which enables us to determine experimentally the value of C for spin 9/2 indium nuclei as C_In~-5 micro-eV. This high value of C is in good agreement with recent theoretical predictions and suggests that the hole-nuclear spin interaction has to be taken into account when considering spin qubits based on holes.
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We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots by pump-probe photo-induced circular dichroism and time-resolved photoluminescence experiments. We show that the hole spin dephasing is controlled by the hyperfine interacti
on between hole and nuclear spins. In the absence of external magnetic field, we find a characteristic hole spin dephasing time of 15 ns, in close agreement with our calculations based on dipole-dipole coupling between the hole and the quantum dot nuclei. Finally we demonstrate that a small external magnetic field, typically 10 mT instead of 200 mT for the case of electrons, quenches the hyperfine hole spin dephasing.
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