2020 Fiscal Year Annual Research Report
Nonlocal quantum metrology based on entanglement and weak measurement
| Project/Area Number |
20F20021
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| Research Institution | Tohoku University |
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Principal Investigator |
枝松 圭一 東北大学, 電気通信研究所, 教授 (10193997)
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| Co-Investigator(Kenkyū-buntansha) |
LE HO 東北大学, 電気通信研究所, 外国人特別研究員
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| Project Period (FY) |
2020-04-24 – 2022-03-31
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| Keywords | 量子計測 / 量子情報 / 量子光学 |
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| Outline of Annual Research Achievements |
We proposed a scheme for the measurement of the product of nonlocal observables: (i) A pair of subsystems is distributed between a bipartite, e.g., Alice and Bob. (ii) They share an entangled measurement apparatus (M). (iii) Both Alice and Bob couple their subsystems into M via the a so-called modular-based measurement, which is controlled rotate gates. (iv) After the interaction, both Alice and Bob will post-select their subsystems onto desire states. (v) The final M state will be measured to obtain the result for the product of nonlocal observables.
This year we proposed a new scheme of nonlocal generalized quantum measurements of bipartite spin products using non-maximally entangled meter. The scheme is resource-efficient and makes it possible to implement the nonlocal, generalized Bell state measurement with variable measurement strength. We generalized the scheme to the variable-strength measurement of nonlocal N-qubit systems. We published the results as a journal paper. Another article was submitted and is in review.
Also investigated are the error-disturbance relation through the backaction of post-selection measurements, and the error-disturbance relation in Faraday rotation measurements of spin systems.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
This year we proposed a new scheme of nonlocal generalized quantum measurements of bipartite spin products using non-maximally entangled meter. We published the results as a journal (NJP) paper. Another article was submitted (in review). We also investigated the error-disturbance relation through the backaction of post-selection measurements. The result was presented in the JPS meeting. In this way, the project is going well as expected.
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| Strategy for Future Research Activity |
We derive a relationship between modular values and nonlocal measurement (nonlocal weak values) by using the Lagrange interpolation. We next discuss how to obtain the modular values from the proposed scheme. Then, we will illustrate the proposed scheme to the quantum paradoxes, which provide us more understanding of quantum mechanics. We also conduct simulation using quantum computing platforms (e.g., IBM-Q) and employ verification experiments with photonics systems.
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