2015 Fiscal Year Annual Research Report
Charge and spin nonlocal interaction in SiGe hybrid cQED architecture
| Project/Area Number |
15H03524
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
デルベック マシュー 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, 特別研究員 (00700121)
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| Co-Investigator(Kenkyū-buntansha) |
樽茶 清悟 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, グループディレクター (40302799)
中島 峻 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, 特別研究員 (60534344)
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| Project Period (FY) |
2015-04-01 – 2018-03-31
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| Keywords | fabrication / characterization / nuclear spins |
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| Outline of Annual Research Achievements |
in the fiscal year FY2015, the main workload was devoted to the development of the device fabrication. Difficulties where unfortunately encountered in the fabrication of the quantum dots. However, the fabrication and characterization of the superconducting resonators went as planned. We succeeded in realizing resonators with quality factors of around 30000, which is one order of magnitude larger than the one realized in GaAs, demonstrating one of the advantages of using SiGe as a two-dimensional gas heterostructure for our hybrid cQED architecture.
As a side work, we studied in detail the the influence of the dynamics of the nuclear spins of the host material on the dephasing of an electronic spin in GaAs (containing 100% of nuclear spins) on short time scales. This work has important implications for the current project : when we will couple an electronic spin in SiGe (interacting with 4.8% of nuclear spins) to photons, the typical interaction time scale will be even shorter, leading to longer coherence times than anticipated and opening the possibility to study the nuclear spins dynamics on even shorter time scales.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
We encountered unexpected difficulties in the fabrication of the quantum dots in the SiGe two-dimensional electron gas heterostructure. As such we could not finalize a fully working device to start the planned experiments. We identified the possible reasons for failing at making working quantum dots and are now implementing the corresponding solutions.
However we could successfully develop the fabrication of the superconducting resonators.
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| Strategy for Future Research Activity |
We identified the possible reasons for not being able to realize working quantum dots in SiGe two-dimensional electron gas heterostructures. In the beginning of the current fiscal year FY2016 we will finalize the fabrication process of the quantum dots. This will be done thanks to our careful analysis of the precedent causes of failure.
We plan to further improve the resonator properties by implementing a new design to counteract the presence of damping slot modes. This design is particularly well suited to our hybrid cQED architecture and we expect to obtain a slot mode reduction as good as or even better than conventional designs currently used.
Once devices are ready, we plan to measure the electron-photon coupling in our architecture and then the non-local current generated between two cavity coupled double quantum dots. We plan to implement a new measurement scheme of the microwave field by doing time resolved measurements of the field quadratures which will give us insights on the intra resonator photon population dynamics. This aspect is challenging but will prove powerful for our project purpose.
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[Journal Article] Quantum Dephasing in a Gated GaAs Triple Quantum Dot due to Nonergodic Noise2016
Author(s)
M.R. Delbecq, T. Nakajima, P. Stano, T. Otsuka, S. Amaha, J. Yoneda, K. Takeda, G. Allison, A. Ludwig, A.D. Wieck, and S. Tarucha
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Journal Title
Physical Review Letters
Volume: 116
Pages: 46802
DOI
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