量子ドット・細線の量子コヒーレンスの検出と制御

2008 Fiscal Year Annual Research Report

• Project/Area Number: 19104007
• Research Institution: The University of Tokyo
• Principal Investigator: 樽茶 清悟 The University of Tokyo, 大学院・工学系研究科, 教授 (40302799)
• Co-Investigator(Kenkyū-buntansha): 大岩 顕 東京大学, 大学院・工学系研究科, 講師 (10321902) ; 山本 倫久 東京大学, 大学院・工学系研究科, 助教 (00376493)
• Keywords: 量子ドット / 電子スピン共鳴 / 量子ビット / InAs自己形成量子ドット / 近藤効果 / 超伝導電流 / コヒーレンス / 量子細線

Research Abstract

1.単一スピンの量子コヒーレンス (1)傾斜磁場法による単一電子スピン共鳴、及び2重量子ドットの2個の電子に個別のスピン共鳴実験に初めて成功した(報道発表)。続けて、Rabi振動実験にも成功し、Rabi型T2時間は1.sec以上であることを確認した。(2)核スピン制御に関して、重要な物理パラメータである交換エネルギーとバイアス電圧の関係を初めて定量的に評価した。ゆらぎ問題に関しては、縦型2重量子ドットの電荷読み出し法、電子スピン-核スピン間のフリップフロップ結合の検出法を開発した。
2,近藤コヒーレンスと超伝導・強磁性の競合 (1)InAs量子ドットについて、昨年度観測したスピン軌道相互作用(SOI)誘起状態分裂の磁場角度依存性を測定し、自己形成ドットに特有な異方的閉じ込めの影響、特定の磁場角度におけるSOI効果の解消、などの重要な知見を得た。(2)超伝導電極と常伝導電極を有するInAsドット試料で、非平衡伝導度測定によりクーパー対伝導に本質的なアンドレーエフ束縛状態の検出に成功した。そのゲート電圧依存性から、基底状態がBCS一重項状態から磁気的二重項状態への相転移、近藤状態とのクロスオーバーなど重要かつ新しい知見を得た。両超伝導電極試料では、近藤温度の大小と超伝導電流の関係(正常接合かπ接合)の詳細を解明中。
3.観測による量子コヒーレンスの破れ (1)ABリングと結合細線の結合系を伝播する電子が、"どちらの細線に存在するか"を2状態とする量子ビットとして使えることを実験的に示した。また、ABリングに近接する量子細線に電流を流して量子ビットに人工的なディフェージングが導できることを確認した。(2)量子ドット中の近藤状態が、近接した量子ポイントコンタクトに流れる電流よって破れることを確認した。しかし、これは量子ドット中のスピンデフェージンではなく、電子温度の上昇で説明できることがわかった。

Research Products

• [Journal Article] Quantitative estimation of exchange interaction energy using two-electron vertical double quantum dots (2009)
  • Author(s): T. Kodera, Ono, Y. Kitamura. Y. Tokura, Y. Arakawa, and S. Tarucha
  • Journal Title: Phya. Rwv. Lett. (in press 掲載確定)
  • Peer Reviewed
• [Journal Article] Trilayer graphene is a semimetal with a gate-tnable band overlap (2009)
  • Author(s): M. F. Craoiun, S. Russo, M. Yamamoto, J. B. Ocatinga, A. F. Morpurgo and S. Yarucha
  • Journal Title: Nature Nanotechnology (in press 掲載確定)
  • Peer Reviewed
• [Journal Article] Realietic model of a vertical pillar quantum dot Analysis of individual dot data (2009)
  • Author(s): P. A. Maksym, Y. Nishi, D. G. Austing, T. Hatano, L. P.Kouwenhoven, H. Aoki, and Tarucha
  • Journal Title: Phys. Rev. B 79 Pages: 115314-115324
  • Peer Reviewed
• [Journal Article] Rectifying behavior in laterally coupled gelt-assembled quantum dots with asymmetric tunneling barriers (2009)
  • Author(s): S. Amaha, T. Kubo, T. Hatano, S. Reraoka, A. Shibatomi, Y. Tokur and S. Tarucha
  • Journal Title: Appl. Phys. Exress 2 Pages: 014501-014503
  • Peer Reviewed
• [Journal Article] Tunneling current through g-factor engineered series quantum dots (2009)
  • Author(s): Y. Tokura, K. Ono, and S. Tarucha
  • Journal Title: phys. Stat. solide(b) 246(4) Pages: 740
  • Peer Reviewed
• [Journal Article] Stability deagrama of laterally coupled triple Vertical quantum dots in triangular arrangement (2009)
  • Author(s): S. Amaha, T. Hatano, T. Kubo, S. Terapka, Y. Tokura, D. O. Austing, and S. Taruchs
  • Journal Title: Appl. Phys. Lett. 94 Pages: 92103
  • Peer Reviewed
• [Journal Article] Coherent Thres-level mixing in an electronic quantumdot (2009)
  • Author(s): C. Payette, G. Yu, J. A. Gupra, D. G. Austing, S. V. Nair, B. Partoens, S. Amaha, and S. Tarucha
  • Journal Title: Phys. Rev. Lett. 102 Pages: 026808-026811
  • Peer Reviewed
• [Journal Article] Selective manipulation of slsctron spins with electric flelds (2008)
  • Author(s): M. Pioro Ladriere, T. Obata, Y. Tokura, Y-S. Shin, T, Kubo, K. Yoshida, T. Taniyama, and S, Tarudha
  • Journal Title: Progress of Theoretical Physics Supplement 176
  • Peer Reviewed
• [Journal Article] InSitu reduction of charge nodse in GaAs/AlxGalhottky gated devices (2008)
  • Author(s): C. Buizert, F. H. L. Koppena, M. Pioro-Ladriere, H. P. Tranits, I. T. Vink, S. Tarucha, W. Wegscheider and I. M. K. Vandersypen
  • Journal Title: Phys. Rev. Lett. 101 Pages: 226603-226606
  • Peer Reviewed
• [Journal Article] Electrcally driven single electron spin resonance in a slanting Zeeman field (2008)
  • Author(s): M. Pioro Ladriere, T. Obata, Y. Tokura, Y-S. Shin, T. Kubo, K. Yoshida, T.Taniyama, and S. Tarucha
  • Journal Title: Nature Physics 4 Pages: 776-779
  • Peer Reviewed
• [Journal Article] Elastic and inelastic tunneling thtough one-slectron and two-electron atates in a vertisal double quantum dot (2008)
  • Author(s): T. Kodara, K. Ono, S. Amaha, Y. Tokura, Y. Arakwa, and S. Tarucha
  • Journal Title: Phydics Stat. Solidi (C ) 5 Pages: 2854-2857
  • Peer Reviewed
• [Journal Article] Eleotron tunneling through single sale-assembled Inas quantum dots coupled to nanogap electrodes (2008)
  • Author(s): K.Shibata, M. Jung, O. Buizert, A. Oiwa, K. Hirakawa, T. Machida, and S. Tarucha
  • Journal Title: Physica Stat. Solede( C ) 8 Pages: 2869-2872
  • Peer Reviewed
• [Journal Article] Laterally eouplde self assenbled InAs quantum dots embedded in resonant tunnel diode with multigate electrodes (2008)
  • Author(s): S. Amaha, T. Hatamo, S. Teraoka, A. Shibatome, S. Tarucha, Y. Nakata, T. Miyazawa, T. Oshima, T. Usuki, and N. Yokoyama
  • Journal Title: Phys. Rev. Lett. 92 Pages: 202109-202111
  • Peer Reviewed
• [Journal Article] Many-body excitations in the tunneling current spectra of a few eleotron quantum dot (2008)
  • Author(s): D. V. Melnikov, T. Fujisawa, D. G. Austing, S. Tarucha and J. P. Levurton
  • Journal Title: Phys, Rev. B77 Pages: 165340-165344
  • Peer Reviewed
• [Journal Article] Spin transport from douvlet state to triplet state in vertioal quantum dots (2008)
  • Author(s): S. M. Huang, H. Akimoto, K. Kono, J. J. Lin, S. Rarucha and K. Ono
  • Journal Title: Jpn. J. Appl. Phys. 47 Pages: 3257-3260
  • Peer Reviewed
• [Journal Article] Electron-spin manipulation and resonator readout in a double quantum-dot nanoelectromechanical system (2008)
  • Author(s): N. Lambert, I. Mahboob,M. Ladrete, Y. Tokura, S. Tarucha, and H. Yamaguchi
  • Journal Title: Phys. Rev. Lett. 100 Pages: 136802-136805
  • Peer Reviewed
• [Journal Article] Coherent pseudo apin resonance in a laterally coupled double quantuma dot (2008)
  • Author(s): T. Kubo, Y. Tokura, and S. Tarucha
  • Journal Title: Physica Stat, Solide( C ) 5 Pages: 170-173
  • Peer Reviewed
• [Journal Article] Two level maxing effectsprobed by rasonant tunnelling through Vertically eoupled quantun dots (2008)
  • Author(s): S. Amaha, C. Payette, J. Gupta, T. Hatano, K. Ono, T. Kodera, Y. Tokura, D. G. Austing, and S, Tarucha
  • Journal Title: Physica stat. Solide ( C ) 5 Pages: 174-177
  • Peer Reviewed
• [Journal Article] Eleotron transport through single silt-assembled InAs quantum dots coupled to superconducting nanogap electrodes (2008)
  • Author(s): K. Shibata, C. Buizert, A. Oiwa, K. Hirakawa, and S. Tarucha
  • Journal Title: Physica stat. Solide ( C ) 5 Pages: 178-181
  • Peer Reviewed
• [Journal Article] Dynamic nuclear polarization in a double quantum dot device:electrical induction and detection (2008)
  • Author(s): J. Baugh, Y. Kitamura, K. Ono, and S. Tarucha
  • Journal Title: Physica stat. Solide ( C ) 5 Pages: 302-305
  • Peer Reviewed
• [Journal Article] Electron transport thtough laterally coupled double quantum dots (2008)
  • Author(s): T. Kubo, Y. Tokura, T. Hatano, and S. Tarcha
  • Journal Title: Controllable Quantum States:Mesoscopic Superconductivity & spintrnics(Mg+s2006), World Scientific Pub co Inc, Proceedings of the Intl. symposium, MTT Basic Res. Les. Lab., Japan 27 Feb-2 Mar 2006, Ed. H. Takayanagi, J. Nitta, and H. Nakano
  • Peer Reviewed
• [Journal Article] Manipulation of Kondo effext by tuning orbital degeneracy (2008)
  • Author(s): S. Amahs, T. Hatano, S. Sasaki, T. Kubo, and Y. Tokura
  • Journal Title: Controllable Quantum States:Mesoscopic Superconductivity & spintrnics(Mg+s2006), World Scientific Pub co Inc, Proceedings of the Intl. symposium, MTT Basic Res. Les. Lab., Japan 27 Feb-2 Mar 2006, Ed. H. Takayanagi, J. Nitta, and H. Nakano
  • Peer Reviewed
• [Journal Article] Coulomb blockade properties of 4-gated quantum dot (2008)
  • Author(s): S. Amahha, T. Hatano, S. Sasaki, T. Kubo, Y. Tokura, and S. Tarucha
  • Journal Title: Controllable Quantum States:Mesoscopic Superconductivity & spintrnics(Mg+s2006), World Scientific Pub co Inc, Proceedings of the Intl. symposium, MTT Basic Res. Les. Lab., Japan 27 Feb-2 Mar 2006, Ed. H. Takayanagi, J. Nitta, and H. Nakano
  • Peer Reviewed
• [Journal Article] Electron spin manipulation in quantum dot systams (2008)
  • Author(s): Y. Tokura, T. Obata, T. Hatano, and S. Tarucha
  • Journal Title: Eleotron Spin Resonance and Related Phenomena in Low-Dimensional Structures, Chap. 2, in the Topic in Applied Physics 115Ed. Marco Fanciull
  • Peer Reviewed
• [Journal Article] Manipulation of exchange coupling in a few-electron double quantum dot
  • Author(s): T. Hatano, S. Amaha, T. Kubo, Y. Tokura, Y. Nishi, Y. Hieayama, and S. Tarucha
  • Journal Title: Phys. Rev. B772008241301-241304
  • Peer Reviewed
• [Presentation] Kondo correlations and Andreev conductande in seif-assemblde InAs quantum dots cortactde with suparconducting and normal leads (2009)
  • Author(s): R. S. Deacon, A. Oiwa, K. Yoshidal K. Shibata, K. Hirakawa, and Tarucha
  • Organizer: 日本物理学会2009年年次大会
  • Place of Presentation: 東京、日本
  • Year and Date: 2009-03-30
• [Presentation] InAs単一自己形成量子ドットにおけるスピン軌道相互作用の定量的評価とその制御 (2009)
  • Author(s): 高橋駿、五十嵐悠一、R.. S. Deacon, 吉田勝治、大岩顕、柴田憲治、平川一彦、樽茶清悟
  • Organizer: 日本物理学会2009年年次大会
  • Place of Presentation: 東京、日本
  • Year and Date: 2009-03-29
• [Presentation] Kondo effect and Andreev Conductance in self-assembled InAs quantum dots contacted with superconducting and normalleads (2009)
  • Author(s): R. S. Deacon, A. Oiwa, K. Yoshida, K. Shibata, K. Hirakawa, and S. Tarucha
  • Organizer: International Sympisium on nanosclae toranxport and technoloby
  • Place of Presentation: 京都、日本
  • Year and Date: 2009-01-21
• [Presentation] Gate tunable proximity supercurrent in self assembide InAs quantum dots (2009)
  • Author(s): R. S. Deacon, Y. Kanai, A. Oiwa, K. Yoshida, K. Shibata, K. Hirakawa, and S. Tarucha
  • Organizer: International Sympisium on nanoselae toransport and technology
  • Place of Presentation: 神奈川、日本
  • Year and Date: 2009-01-20
• [Presentation] Quantitative evaluation and tuning of spin-orbit interaction in InAs self-assembled quantum dots (2009)
  • Author(s): S. Takahashi, Y. Igarashi, R. S. Deacon, K. Yoshidal A. Oiwa, K. Shibate, K. Hirakawa, and S. Tarucha
  • Organizer: International Sympisium on nanosclas toransport and technoligy
  • Place of Presentation: 京都、日本
  • Year and Date: 2009-01-20
• [Presentation] 自己形成InAs量子ドット/超伝導接合系における超伝導電流の観測 (2008)
  • Author(s): 金井康、Russell, S. Deacon, 吉田勝治、柴田憲治、平川一彦、大岩顕、樽茶清悟
  • Organizer: 日本物理学会2008年秋季大会
  • Place of Presentation: 岩手、日本
  • Year and Date: 2008-09-20
• [Presentation] InAs単一自己形成量子ドットにおけるスピン軌道相互作用の定量的評価 (2008)
  • Author(s): 高橋駿、五十嵐悠一、R. S. Deacon、 大岩顕、柴田憲治、平川一彦。樽茶清悟
  • Organizer: 日本物理学会2008年秋季大会
  • Place of Presentation: 岩手、日本
  • Year and Date: 2008-09-20
• [Presentation] Quantitative evaluation of spin-orbit interaction in InAs quantum dots (2008)
  • Author(s): S. Takahashi, Y. Igarashi, R. S. Deacon, A. Oiwa. K. Shibata, K, Hirakawa, and S. Tarucha
  • Organizer: 25th International Conference on Physics of Low temperature (LT25)
  • Place of Presentation: Amsterdam, Holland
  • Year and Date: 2008-09-12
• [Presentation] Kondo Effect and Superconductivity Observed in Single InAs Qusntum Dots Coupled to Superconducting Leads (2008)
  • Author(s): S. Tarucha
  • Organizer: ISQM-Tokyo'08
  • Place of Presentation: 埼玉、日本
  • Year and Date: 2008-08-28
• [Presentation] Observation of suppercurrent in single InAs self-assembled quntum dots coupled to superconducting leads Supercurrent in single InAs quantum dots coupled to aluminium electrodes (2008)
  • Author(s): Y. Kanai, R. S. Frsvon, K. Yoshida, K. Shibata, K. Hirakawa, A. Oiwa, and S. Tarucha
  • Organizer: 25th International Confersnce on Physics of Low temperature(LT25)
  • Place of Presentation: Amsterdam, Holland
  • Year and Date: 2008-08-07
• [Presentation] Supercurrent in single InAs quantum dots coupled to aluminiume lectrode (2008)
  • Author(s): R. S. Deacon, Y. Kanai, A. Oiwa, K. Yoshida, K. Shibata, K. Hirakawa, and S. Tarucha
  • Organizer: 29th Intemational Conference on Semiconductor Physics (ICPS2008)
  • Place of Presentation: Rio de Janeiro, Brazil
  • Year and Date: 2008-07-31
• [Patent(Industrial Property Rights)] 量子ドットを用いた電子装置 (2008)
  • Inventor(s): ビオロラドリエル・ミシェル、小幡利顕、申潤錫、久保敏弘、樽茶清悟
  • Industrial Property Rights Holder: JST
  • Industrial Property Number: PCT/JP2008/072035
  • Filing Date: 2008-12-04
  • Overseas
• [Patent(Industrial Property Rights)] 二重量子ドット帯電型整流器 (2008)
  • Inventor(s): 天羽真一、久保敏弘、羽田野剛司、寺岡総一郎、柴富昭洋、樽茶清悟
  • Industrial Property Rights Holder: JST
  • Industrial Property Number: 特願2008-160932
  • Filing Date: 2008-06-19