2017 Fiscal Year Research-status Report
Spin hot spots in semiconductor quantum dots
| Project/Area Number |
16K05411
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
STANO PETER 国立研究開発法人理化学研究所, 創発物性科学研究センター, 上級研究員 (10722746)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | スピン 物性 (半導体) / spin-orbit coupling / decoherence / quantum dot / spin qubit |
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| Outline of Annual Research Achievements |
We have used the in-plane magnetic fields to separate the effects of the nuclear fields and spin-orbit fields. With that, we were able to extract structural information on a semiconducting quantum dot. Further, we also investigated the co-tunneling dynamics in quantum dots in contact with reservoir. Related to that, we showed how the tunneling to and from a reservoir could be used for a very-high-fidelity single-shot spin measurement which are crucial for quantum information processing. Finally, we established a theory of dynamical nuclear polarization induced by a quantum point contact, and spin-dependent scatterer in general, which can serve for detection and sensing on nanoscale.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The primary goals that I had set up in the project relating to the quantum dots based on the conduction band in GaAs are now finished. Namely, we have found the method to extract the spin-orbit fields, which has been successfully implemented experimentally. We also identified conditions for optimal geometries of quantum dots in such material. I am at the moment working on an extension of these methods to extract further information on the quantum dot, namely the shape and orientation of the quantum mechanical orbitals. It would be of high practical importance, allowing tuning the quantum dot confinement in situ. The remaining goals pertain to other materials, like Si, and different configurations, like quantum dots based on valence band particles.
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| Strategy for Future Research Activity |
In the last year, I will extend the work done for the conduction band of III-V zinc-blende material (GaAs) to other materials (of the IV group, e.g., silicon or germanium) and valence bands. Namely, both of these appeared recently as a potential solution to the problem of nuclear spins inherent in III-V materials. There are many recent experiments with spin qubits in quantum dots in these new materials and configurations, but the dominant decoherence mechanism there is still unknown. It is of high importance to identify it. I suspect that it will be the charge noise, entering through the spin-orbit coupling. My previous investigations in this project are an ideal basis to examine this question. I plan to apply the acquired knowledge, especially the description developed in [6], to the spin effects in crystals with Td symmetry (Si, Ge), and to the valence band in both group IV and group III-V material.
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| Causes of Carryover |
I plan to use the remaining budget for other costs, mostly for pruchasing books.
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