- 著者
- Tomimoto Shinichi Kawana Keisuke Murakami Akira Masumoto Yasuaki
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of Luminescence (ISSN:00222313)
- 巻号頁・発行日
- vol.133, pp.162-168, 2013-01
- 被引用文献数
- 1
We have experimentally observed the spin polarization process of single electrons in InP/InGaP quantum dots by time-resolved Kerr rotation measurements. It is found that the inversion of the spin polarization direction occurs with the variation of the intensity of the optical pulse. The spin coherence lifetime abruptly changes on the occurrence of the inversion. We have reproduced the inversion in numerical simulations using the density operator of the electron–trion four-level system, assuming a small deviation of the optical pulse from circular polarization. The change of the spin lifetime is attributed to the qualitative change of the four-level system in the electric polarization state.
- 著者
- Tomimoto Shinichi Kawana Keisuke Murakami Akira Masumoto Yasuaki
- 出版者
- American Physical Society
- 雑誌
- Physical review B (ISSN:10980121)
- 巻号頁・発行日
- vol.85, no.23, pp.235320, 2012-06
We have experimentally studied the spin dynamics of excitons, electrons, and trions in charge-tunable InP/InGaP quantum dots (QDs) excited by picosecond resonant laser pulses by observing the time-resolved Kerr rotation. In singly charged QDs, inversion of the spin polarization direction of doped electrons is found to be caused simply by variation in the pulse intensity, which is accompanied by an abrupt change of the spin coherence time. This phenomenon is reproduced by density-matrix calculations allowing for the reaction on the QD electron-trion four-level system during its coherent radiation emission. This result means that the optical coherence is another critical factor affecting electron spin coherence.