Spin coherence generation in negatively charged self-assembled (In,Ga)As quantum dots by pumping excited trion states

Autor(es)

Henriques, A. B. ^[1] ; Schwan, A. ^[2] ; Varwig, S. ^[2] ; Maia, A. D. B. ^[1] ; Quivy, A. A. ^[1] ; Yakovlev, D. R. ^[2] ; Bayer, M. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo - Brazil

^[2] Tech Univ Dortmund, D-44221 Dortmund - Germany

• Tipo de documento: Artigo Científico
• Fonte: Physical Review B; v. 86, n. 11 SEP 28 2012.
• Citações Web of Science: 4

Resumo

Spin coherence generation in an ensemble of negatively charged (In,Ga)As/GaAs quantum dots was investigated by picosecond time-resolved pump-probe spectroscopy measuring ellipticity. Robust coherence of the ground-state electron spins is generated by pumping excited charged exciton (trion) states. The phase of the coherent state, as evidenced by the spin ensemble precession about an external magnetic field, varies relative to spin coherence generation resonant with the ground state. The phase variation depends on the pump photon energy. It is determined by (a) pumping dominantly either singlet or triplet excited states, leading to a phase inversion, and (b) the subsequent carrier relaxation into the ground states. From the dependence of the precession phase and the measured g factors, information about the quantum dot shell splitting and the exchange energy splitting between triplet and singlet states can be extracted in the ensemble. (AU)

• Processo FAPESP: 10/10452-8 - Espectroscopia de harmônicos múltiplos, orientação de spin e magnetização instantânea utilizando-se a luz
• Beneficiário: Andre Bohomoletz Henriques
• Modalidade de apoio: Auxílio à Pesquisa - Regular