| Project/Area Number |
14340028
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General mathematics (including Probability theory/Statistical mathematics)
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| Research Institution | Tohoku University |
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Principal Investigator |
OZAWA Masanao Tohoku University, Graduate School of Information Sciences, Professor, 大学院・情報科学研究科, 教授 (40126313)
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| Co-Investigator(Kenkyū-buntansha) |
HIAI Fumio Tohoku University, Graduate School of Information Sciences, Professor, 大学院・情報科学研究科, 教授 (30092571)
OBATA Nobuaki Tohoku University, Graduate School of Information Sciences, Professor, 大学院・情報科学研究科, 教授 (10169360)
TAYA Hisao Tohoku University, Graduate School of Information Sciences, Research Associate, 大学院・情報科学研究科, 助手 (40257241)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥11,400,000 (Direct Cost: ¥11,400,000)
Fiscal Year 2004: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2003: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | uncertainty principle / quantum measurement / quantum computing / quantum information / conservation law / completely positive maps / quantum gates / fault-tolerant quantum computing / 量子完全相関 / 量子回路 / 量子Turing機械 / 量子推定理論 / 量子Fisher情報量 / 測定誤差 / 擾乱 / Wigner-Araki-Yanaseの定理 / 制御否定ゲート |
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| Research Abstract |
1.Heisenberg's uncertainty principle, which gives the trade-off between measurement noise and disturbance, has been reconsidered. Its limitation of the validity has been clarified and the universally valid generalization (universal uncertainty principle) has been established. If any measuring apparatus measures an observable A with noise ε(A) and disturbance η(B) on B, we have the relation ε(A)η(B)+ε(A)σ(B)+σ(A)η(B)≧(1/2)|<[A,B]>|, where σ stands for the standard deviation in the state just before the measurement.
2.It has been shown that, if the noise ε(A) and the disturbance η(B) are statistically independent from the initial state of the measured object, we have the original Heisenberg relation ε(A)η(B)≧(1/2)|<[A,B]>|.
3.From the universal uncertainty principle, Wigner-Araki-Yanase (WAY), found in 1952 to set a limitation of measurements under conservation law, has been quantitatively generalized to a reciprocal relation between the mean-square-noise of the measurement and the variance of the conserved quantity.
4.As a consequence from the universal uncertainty principle, it has been shown that the angular momentum conservation law sets a limitation to the accuracy of quantum gate operations, the accuracy of the CNOT gate controlled by an interaction with n qubit ancilla system is limited with error probability at least 1/(4n^2), and the CNOT controlled by the electro-magnetic field with average photon N is limited with error probability at least 1/(16N).
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