2007 Fiscal Year Final Research Report Summary
Study on precision measurement of angular momentum entangled photon states
| Project/Area Number |
18560032
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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 |
Applied optics/Quantum optical engineering
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
MIYAMOTO Yoko The University of Electro-Communications, Faculty of Electro-Communications, Assistant Professor (50281655)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEUCHI Shigeki Hokkaido University, Research Institute for Electronic Science, Professor (80321959)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Applied quantum optics / Quantum electronics / Cryptography / Quantum computer / Optical source / Entanglement / Optical orbital angular momentum / Laguerre Gaussian beam |
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| Research Abstract |
We proposed a new measurement system for photons entangled in orbital angular momentum (OAM), with the aim to carry out precision measurement of angular momentum entangled photon states. The system combines an OAM detection/transformation system using hologram, a superposition state detection system using interferometer, and quantum correlation detection by coincidence photon counting. The measurement targets were parametric fluorescence photon pairs, and we focused on a subspace comprising two OAM states each for the signal and idler photons. The following results were obtained.
1. A quantum correlation detection experiment using our interferometric system for the idler photon and the conventional hologram shifting method for the signal photon successfully showed OAM entanglement. Correspondence between the measurement basis chosen by our interferometric system and that chosen by the conventional method was confrmed.
2. We showed that with our proposed interferometric system, misdetection of untargeted OAM components can be reduced to below 0.4% in terms of relative detection efficiency. This is a clear improvement over the conventional method.
3. We refined our system by improving the holograms and optical axis alignment. A new quantitative measure of hologram distortion was defined and used as a feedback to the hologram design.
4. We clarified the effect of Gouy phase in detection of OAM entangled photon pairs, and proposed a new method to manipulate OAM superposition photon states.
5. We examined theoretically the generation and detection of higher dimensional entanglement involving 3 or more OAM states for both the signal and idler photons, taking into consideration effect of finite crystal length. We clarified the effect of higher dimensional entanglement on coincidence count rate distribution obtained by the hologram shifting method. We also found that the position of maximum coincidence shifts with the increase of crystal length.
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