2003 Fiscal Year Annual Research Report

量子ドットの電子スピン光操作による量子演算の研究

Research Project

Project/Area Number	14076201
Research Institution	Hokkaido University
Principal Investigator	武藤俊一北海道大学, 大学院・工学研究科, 教授 (00114900)
Co-Investigator(Kenkyū-buntansha)	白峰賢一北海道大学, 大学院・工学研究科, 助手 (10241358) 戸田泰則北海道大学, 大学院・工学研究科, 助教授 (00313106) 足立智北海道大学, 大学院・工学研究科, 助教授 (10221722)
Keywords	電子スピン / 量子ドット / 量子演算 / 励起子間相互作用
Research Abstract	量子ドットの電子スピンは将来の大規模量子コンピューティング実現へ向けての有力候補の一つである.特に光半導体を用いた量子ドットでは,光による電子スピンの制御が容易で量子情報光通信との整合性が良いという大きな長所を持つ.報告者らは量子ドットの電子スピンの光支援トンネル(ラビ振動)とそのクーロンブロッケイドを用いた量子演算を独自に提案している.今年度は、結合量子ドットにおける電子スピンのトンネルをフォトン支援トンネリングにより実現することを目的に,まずは自己組織化量子ドットにおける共鳴励起条件でのスピン緩和時間の測定および結合量子ドットの作製とその(フォノン支援)トンネルによるスピンの分極と緩和の測定を行った.提案している量子ドットの電子スピンを用いた量子演算ゲートの実現に向けて,四光波混合による量子ドットの共鳴励起でのスピン緩和時間測定,および構想の基本となる結合量子ドットの作製を行い,その光学特性を評価した. 結合量子ドットからの発光の時間変化にはキャリアのトンネルの効果が明瞭に認められ、スピン緩和の層間厚依存性がk^3項(いわゆるドレッセルハウス項)によって説明できることがわかった.特に低エネルギー側に基底準位があるドットにおけるスピン緩和特性を調べたところ3nsという長い緩和時間を得た. また四光波混合法による共鳴励起下での量子ドットのスピン緩和を測定し、共鳴励起下でスピン緩和時間が2倍程度長くなることを確認した。さらにドット内の電子スピン偏極を通して形成される原子核スピン偏極の電子エネルギー準位への影響を調べるために、偏光依存磁気発光測定を行い、0.3Tの核磁場を観測し、その制御性についての実験的研究をおこなった。

Research Products

(17 results)

All Other

All Publications (17 results)

[Publications] H.Sasakura, S.Adachi, S.Muto, T.Usuki (他1名): "Coulomb interaction in asymmetric triple-coupled quantum dots"Semiconductor Science and Technology. 19. S409-S411 (2004)
[Publications] O.Ikeuchi, S.Adachi, Sasakura, S.Muto: "Observation of population transfer to dark exciton states by using spin-diffracted four-wave mixing"Journal of Applied Physics. 93. 9634-9638 (2003)
[Publications] H.Sasakura, S.Adachi, S.Muto: "Quantum gates based on electron spins of triple quantum dot"Japanese Journal of Applied Physics. 42. 6308-6313 (2003)
[Publications] H.Sasakura, S.Adachi, S.Muto, H.Z.Song (他2名): "Carrier tunneling in asymmetric double quantum dots"Physica E. 21. 511-515 (2003)
[Publications] H.Sasakura, S.Adachi, S.Muto, H.Song (他2名): "Spin depolarization via tunneling effects in asymmetric double quantum dot structures"Japanese Journal of Applied Physics. (in press). (2004)
[Publications] S.Adachi, S.Maki, O.Ikeuchi, H.Sasakura, S.Muto: "Spin-diffracted four-wave mixing measurements of exciton spin relaxation and population transfer to dark states"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 241-248 (2003)
[Publications] S.Adachi, S.Muto, K.Hazu, T.Sota, K.Suzuki (他2名): "Exciton-exciton interaction and hetro-biexciton in GaN"Physical Review B. 67. 205212/1-205212/5 (2003)
[Publications] S.Adachi, H.Sasakura, S.Muto, K.Hazu, T.Sota (他2名): "Exciton-exciton correlation effects on FWM in GaN"physica status solidi (b). 240. 348-351 (2003)
[Publications] K.Hazu, T.Sota, K.Suzuki, S.Adachi, SF.Chichibu (他4名): "Strong biexcitonic effects and exciton-exciton correlations in bulk ZnO"Physical Review B. 68. 033205/1-033205/5 (2003)
[Publications] S.Adachi, K.Hazu, T.Sota, SF.Chichibu (他4名): "Biexciton formation and exciton-exciton correlation effects in bulk ZnO"Semiconductor Science and Technology. 19. S276-S278 (2004)
[Publications] S.Adachi, K.Hazu, T.Sota, SF.Chichibu (他3名): "Scattering processes and dynamics of exciton-biexciton system in GaN"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 188-201 (2003)
[Publications] K.Hazu, T.Sota, K.Suzuki, S Adachi, S.F.Chichibu: "Optical nonlinearities of excitons in ZnO single crystal"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 257-263 (2003)
[Publications] K.Hazu, K.Torii, T.Sota, S.Adachi (他4名): "Impact of the k-linear term on nonlinear optical response of the C-exciton manifold in ZnO"Journal of Applied Physics. (accepted). (2004)
[Publications] Y.Toda, T.Matsubara, R.Morita, M.Yamashita (他3名): "Two-photon absorption and multiphoton-induced photoluminescence of bulk GaN excited below the middle of the bandgap"Applied Physics Letters. 82. 4713-4715 (2003)
[Publications] Y.Toda, I.Matsubara, R.Morita, K.Hoshino (他2名): "Efficient two-photon absorption of bulk GaN in the near-infrared region"physica status solidi (c). 0. 2627-2630 (2003)
[Publications] T.Inoue, Y.Toda, K.Hoshino, T.Someya (他1名): "Raman study of the strain in GaN films by comparison with a free-standing GaN"physica status solidi (c). 0. 2428-2431 (2003)
[Publications] Y.Toda, R.Morita, T Nakaoka, (他3名): "Selective excitation of self-assembled quantum dots by using shaped pulse"Physica E. 21/2-4. 180-183 (2004)

2003 Fiscal Year Annual Research Report

量子ドットの電子スピン光操作による量子演算の研究

Principal Investigator

武藤 俊一 北海道大学, 大学院・工学研究科, 教授 (00114900)

Research Products

[Publications] H.Sasakura, S.Adachi, S.Muto, T.Usuki (他1名): "Coulomb interaction in asymmetric triple-coupled quantum dots"Semiconductor Science and Technology. 19. S409-S411 (2004)

[Publications] O.Ikeuchi, S.Adachi, Sasakura, S.Muto: "Observation of population transfer to dark exciton states by using spin-diffracted four-wave mixing"Journal of Applied Physics. 93. 9634-9638 (2003)

[Publications] H.Sasakura, S.Adachi, S.Muto: "Quantum gates based on electron spins of triple quantum dot"Japanese Journal of Applied Physics. 42. 6308-6313 (2003)

[Publications] H.Sasakura, S.Adachi, S.Muto, H.Z.Song (他2名): "Carrier tunneling in asymmetric double quantum dots"Physica E. 21. 511-515 (2003)

[Publications] H.Sasakura, S.Adachi, S.Muto, H.Song (他2名): "Spin depolarization via tunneling effects in asymmetric double quantum dot structures"Japanese Journal of Applied Physics. (in press). (2004)

[Publications] S.Adachi, S.Maki, O.Ikeuchi, H.Sasakura, S.Muto: "Spin-diffracted four-wave mixing measurements of exciton spin relaxation and population transfer to dark states"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 241-248 (2003)

[Publications] S.Adachi, S.Muto, K.Hazu, T.Sota, K.Suzuki (他2名): "Exciton-exciton interaction and hetro-biexciton in GaN"Physical Review B. 67. 205212/1-205212/5 (2003)

[Publications] S.Adachi, H.Sasakura, S.Muto, K.Hazu, T.Sota (他2名): "Exciton-exciton correlation effects on FWM in GaN"physica status solidi (b). 240. 348-351 (2003)

[Publications] K.Hazu, T.Sota, K.Suzuki, S.Adachi, SF.Chichibu (他4名): "Strong biexcitonic effects and exciton-exciton correlations in bulk ZnO"Physical Review B. 68. 033205/1-033205/5 (2003)

[Publications] S.Adachi, K.Hazu, T.Sota, SF.Chichibu (他4名): "Biexciton formation and exciton-exciton correlation effects in bulk ZnO"Semiconductor Science and Technology. 19. S276-S278 (2004)

[Publications] S.Adachi, K.Hazu, T.Sota, SF.Chichibu (他3名): "Scattering processes and dynamics of exciton-biexciton system in GaN"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 188-201 (2003)

[Publications] K.Hazu, T.Sota, K.Suzuki, S Adachi, S.F.Chichibu: "Optical nonlinearities of excitons in ZnO single crystal"Proceedings of SPIE, Ultrafast Phenomena in Semiconductors VII. 4992. 257-263 (2003)

[Publications] K.Hazu, K.Torii, T.Sota, S.Adachi (他4名): "Impact of the k-linear term on nonlinear optical response of the C-exciton manifold in ZnO"Journal of Applied Physics. (accepted). (2004)

[Publications] Y.Toda, T.Matsubara, R.Morita, M.Yamashita (他3名): "Two-photon absorption and multiphoton-induced photoluminescence of bulk GaN excited below the middle of the bandgap"Applied Physics Letters. 82. 4713-4715 (2003)

[Publications] Y.Toda, I.Matsubara, R.Morita, K.Hoshino (他2名): "Efficient two-photon absorption of bulk GaN in the near-infrared region"physica status solidi (c). 0. 2627-2630 (2003)

[Publications] T.Inoue, Y.Toda, K.Hoshino, T.Someya (他1名): "Raman study of the strain in GaN films by comparison with a free-standing GaN"physica status solidi (c). 0. 2428-2431 (2003)

[Publications] Y.Toda, R.Morita, T Nakaoka, (他3名): "Selective excitation of self-assembled quantum dots by using shaped pulse"Physica E. 21/2-4. 180-183 (2004)

武藤俊一北海道大学, 大学院・工学研究科, 教授 (00114900)