2001 Fiscal Year Final Research Report Summary
Study on quantum communication using femto-seconds pulses
| Project/Area Number |
12640394
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物理学一般
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| Research Institution | Gakusyuin University |
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Principal Investigator |
HIRANO Takuya Gakusyuin University, Dept. of Science, Assoc. Prof., 理学部, 助教授 (00251330)
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| Project Period (FY) |
2000 – 2001
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| Keywords | femtosecond pulse / parametric amplification / squeezed states / guasi-phase matching / quantum communication / quantum teleportation / quantum cryptography |
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| Research Abstract |
We have achieved the following results.
(1) We obtained more than 40% conversion efficiency for the second harmonic generation of a mode-locked YVO_4 laser using a quasi-phase-matched periodically-polled KTiO_4 (PPKTP) crystal.
(2) We observed 10% parametric gain using a femtosecond Ti:sapphire laser and β-BaB_2O_4 crystal.
(3) We obtained parametric gain of 10.4 dB and -3.2 dB squeezing using a PPKTP crystal.
(4) We have developed an optical coupling system using a gradient index micro lens which enables good coupling efficiency for a periodically polled LiNbO_3 waveguide, and observed second harmonic generation.
(5) We have developed a balanced homodyne detector based on a commercial amplifier with which we could observe vacuum fluctuations using pulsed local oscillator.
(6) We have achieved quantum key distribution over a 1 km optical fiber using pulsed homodyne detection. We show that quantum cryptography based on homodyne detection is secure against individual beam-splitting attack.
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