title: Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot.
abstract: We demonstrate that efficient optical pumping of nuclear spins in semiconductor quantum dots (QDs) can be achieved by resonant pumping of optically forbidden transitions. This process corresponds to one-to-one conversion of a photon absorbed by the dot into a polarized nuclear spin, and also has potential for initialization of hole spin in QDs. We find that by employing this spin-forbidden process, nuclear polarization of 65% can be achieved, markedly higher than from pumping the allowed transition, which saturates due to the low probability of electron-nuclear spin flip-flop.
authors.affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.
authors.forename: E A
authors.initials: EA
authors.lastname: Chekhovich
authors.forename: M N
authors.initials: MN
authors.lastname: Makhonin
authors.forename: K V
authors.initials: KV
authors.lastname: Kavokin
authors.forename: A B
authors.initials: AB
authors.lastname: Krysa
authors.forename: M S
authors.initials: MS
authors.lastname: Skolnick
authors.forename: A I
authors.initials: AI
authors.lastname: Tartakovskii