Study on quantum dot photon emitter and its application to free-space quantum key distribution

2008 Fiscal Year Final Research Report

• Project/Area Number: 18681025
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Microdevices/Nanodevices
• Research Institution: Hokkaido University
• Principal Investigator: KUMANO Hidekazu Hokkaido University, 電子科学研究所, 准教授 (70292042)
• Project Period (FY): 2006 – 2008
• Keywords: 単量子デバイス

Research Abstract

将来の量子鍵配送システム全体として考えた場合、ファイバー系と相補的な役割が期待される空間伝送量子鍵配送に向け、大気の透過率が高くかつSi 単一光子検出器の検出感度とマッチングの良いナノ構造として単一In0.75Al0.25As 量子ドットを形成し、励起エネルギー選択による純度の高い単一光子発生を実現した。さらに、後段での暗号化の際の偏光変調のため高い円偏光度を持つ単一光子の発生を実現した。すなわち、発光エネルギーに対して光学フォノンのエネルギー分高い準位を共鳴的に励起した場合、零磁場中にもかかわらず0.85 と著しい円偏光度の上昇が観測され、電子スピンと光子偏光の間での高効率での状態変換が可能であることが示された。レート方程式解析の結果、InAs LO フォノン共鳴励起下ではスピン反転確率が7.5%以下に抑制され、また荷電励起子基底状態におけるスピン緩和時間は発光再結合寿命の11 倍程度であることが判った。この値は中性励起子のスピン反転時間の約3 倍であり、交換相互作用の無い荷電励起子におけるスピン状態の安定化という、応用に向けて重要な特徴が顕在化された結果と考えられる。これらの成果は、波長短波化した量子ドットによる空間伝送量子暗号通信への展開を展望する上で、非常に大きな意義を持つ。

Research Products

• [Journal Article] Excitonic spin-state preservation mediated by optical-phonon resonant excitation in a single quantum dot (2008)
  • Author(s): H. Kumano, H. Kobayashi, S. Ekuni, Y. Hayashi, M. Jo, H. Sasakura, S. Adachi, S. Muto, and I. Suemune
  • Journal Title: Phys. Rev B 78 Pages: 081306-1-4
  • Peer Reviewed
• [Journal Article] Highly circular-polarized single photon generation from a single quantum dot at zero magnetic field (2008)
  • Author(s): H. Kobayashi, H. Kumano, M. Endo, M. Jo, I. Suemune, H. Sasakura, S. Adachi, and S. Muto
  • Journal Title: Microelectron. Journal 39 Pages: 327-330
  • Peer Reviewed
• [Journal Article] Single photon emission with high degree of circular polarization from a single quantum dot under zero magnetic field (2008)
  • Author(s): H. Kumano, H. Kobayashi, Y. Hayashi, M. Jo, I. Suemune, H. Sasakura, S. Adachi, and S. Muto
  • Journal Title: Physica E 40 Pages: 1824-1827
  • Peer Reviewed
• [Journal Article] Deterministic single-photon and polarization-correlated photon pair generations from a single InAlAs quantum dot (2006)
  • Author(s): H. Kumano, S. Kimura, M. Endo, H. Sasakura, S. Adachi, S. Muto, and I. Suemune
  • Journal Title: J. Nanoelectron. Optoelectron 1 Pages: 39-51
  • Peer Reviewed
• [Journal Article] Triggered single-photon emission and cross-correlation properties in InAlAs quantum dot (2006)
  • Author(s): H. Kumano, S. Kimura, M. Endo, I. Suemune, H. Sasakura, S. Adachi, S. Muto, H. Z. Song, S. Hirose, and T. Usuki
  • Journal Title: Physica E 32 Pages: 144-147
  • Peer Reviewed
• [Journal Article] Origin of asymmetric splitting of a neutral exciton in a single semiconductor quantum dot (2006)
  • Author(s): I. Suemune, H. Kumano, S. Kimura, H. Sasakura, S. Adachi, S. Muto, H. Z. Song, S. Hirose, and T. Usui
  • Journal Title: phys. Stat. sol c 3 Pages: 3908-3911
  • Peer Reviewed
• [Presentation] Photon-state conversion with well-defined spin states in a single quantum dot without magnetic field (2008)
  • Author(s): H. Kumano, S. Ekuni, H. Sasakura, S. Adachi, S. Muto, and I. Suemune
  • Organizer: 29th International Conference on the Physics of Semiconductors
  • Place of Presentation: Rio de Janeiro, Brazil
  • Year and Date: 20080727-0801
• [Presentation] Spin-flip quenching during energy relaxation processes mediated by optical-phonons in a single quantum dot (2008)
  • Author(s): H. Kumano, H. Kobayashi, S. Ekuni, H. Sasakura, I. Suemune, S. Adachi and S. Muto
  • Organizer: The 5th International Conference on Semiconductor Quantum Dots
  • Place of Presentation: Gyeongju, Korea
  • Year and Date: 20080511-16
• [Presentation] Optical-phonon Mediated Efficient Spin-state Transfer between Electron-spin and Photon-polarization with a Single Quantum Dot without External Field (2008)
  • Author(s): H. Kumano, S. Ekuni, H. Kobayashi, H. Sasakura, I. Suemune, S. Adachi and S. Muto
  • Organizer: 8th International Conference on Physics of Light-Matter Coupling in Nanostructures
  • Place of Presentation: Tokyo, Japan
  • Year and Date: 20080407-11
• [Presentation] Photon Generations from Semiconductor Quantum Dots and Their Applications to Next-Generation Information Technology (2008)
  • Author(s): I. Suemune, H. Kumano, Y. Hayashi, M. Jo, and Y. Idutsu
  • Organizer: 2008 International Symposium on Global COE Program of Center for Next-Generation Information Technology based on Knowledge Discovery and Knowledge Federation
  • Place of Presentation: Sapporo, Japan
  • Year and Date: 20080122-23
• [Presentation] High degree of circular polarization single photon emission from a single quantum dot under non-resonant excitation and zero magnetic field (2007)
  • Author(s): H. Kumano, H. Kobayashi, Y. Hayashi, M. Endo, I. Suemune, H. Sasakura, S. Adachi, and S. Muto
  • Organizer: International conference on Modulated Semiconductor Structures
  • Place of Presentation: Genova, Itary
  • Year and Date: 20070715-20
• [Presentation] Highly circular-polarized photon generation from a single quantum dot at zero magnetic field (2007)
  • Author(s): H. Kobayashi, H. Kumano, M. Endo, M. Jo, I. Suemune, H. Sasakura, S. Adachi, and S. Muto
  • Organizer: The Sixth international Conference on Low Dimensional Structures and Devices
  • Place of Presentation: The Archipelago of San Andres, COLOMBIA
  • Year and Date: 20070415-20
• [Presentation] Polarization preservation between a photon pair from biexciton-exciton cascaded decay process in a single InAlAs quantum dot (2006)
  • Author(s): H. Kumano, S. Kimura, M. Endo, S. Adachi, H. Sasakura, S. Muto, and I. Suemune
  • Organizer: 28th International conference on the Physics of Semiconductors
  • Place of Presentation: Vienna, Austria
  • Year and Date: 20060724-28
• [Remarks]
  • URL: http://nanophoto.es.hokudai.ac.jp/