2006 Fiscal Year Final Research Report Summary
Study on optical quantum information processing
| Project/Area Number |
16204031
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
原子・分子・量子エレクトロニクス・プラズマ
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| Research Institution | National Institute of Informatics |
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Principal Investigator |
YAMAMOTO Yoshihisa National Institute of Informatics, Principles of Informatics Research Division, Professor, 情報学プリンシプル研究系, 教授 (60370102)
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| Co-Investigator(Kenkyū-buntansha) |
NEMOTO Kae National Institute of Informatics, Principles of Informatics Research Divisionfa, Associate Professor, 情報学プリンシプル研究系, 助教授 (80370104)
MATSUMOTO Keiji National Institute of Informatics, Principles of Informatics Research Division, Associate Professor, 情報学プリンシプル研究系, 助教授 (60272390)
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| Project Period (FY) |
2004 – 2007
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| Keywords | Quantum computer / Quantum electronics / Foundations of Informatics / Linear optics quantum information processing / Electron spin / Decoherence / Donor impurity |
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| Research Abstract |
Quantum information processing based on weak optical nonlinearity is a promising and practical approach compared to all linear optics quantum information processing, because a required physical resource can be dramatically reduced in this way. In this project we have studied three-level Lamda system provided by donor impurities in semiconductors. A donor impurity in semiconductor captures one un-paired electron at low temperatures and becomes electrically neutral (D^0). Under a dc magnetic field, the bound electron spin states are split by a Zeeman frequency, which constitute a metastable ground states (qubit). Under optical excitation of excitons, the neutral donor captures one exciton and forms a new state, called a donor bound exciton (DoX). The reason why we focused on this system as a source of weak optical nonlinearity is primarily its small inhomogeneous linewidth (~1GHz), which is three-four orders of magnitude smaller than self-assembled quantum dot systems. We mainly studied a donor bound electron/exciton system in GaAs with a density as low as 10^<13> (cm^<-3>). We could demonstrate the coherent population trapping (dark state) experiment, nuclear field induced dephasing effect (T^*_2 ~ few nsec), long T_1 time constant (~4msec), and single Raman pulse induced Rabi oscillation of electron spin states. We have also studied ^<19>F donor impurities in ZnSe matrix and obtained a similar result. These experimental results show that a donor bound electron/ exciton system is a promising candidate as a source of weak optical nonlinearity for quantum information processing.
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