| 研究課題/領域番号 |
20F20757
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| 研究種目 |
特別研究員奨励費
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| 配分区分 | 補助金 |
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| 応募区分 | 外国 |
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| 審査区分 |
小区分13020:半導体、光物性および原子物理関連
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| 研究機関 | 東京大学 |
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研究代表者 |
中村 泰信 東京大学, 大学院工学系研究科(工学部), 教授 (90524083)
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| 研究分担者 |
CHANG CHUNG WAI SANDBO 東京大学, 大学院工学系研究科(工学部), 外国人特別研究員
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| 研究期間 (年度) |
2020-07-29 – 2023-03-31
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| 研究課題ステータス |
完了 (2022年度)
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| 配分額 *注記 |
2,200千円 (直接経費: 2,200千円)
2022年度: 500千円 (直接経費: 500千円)
2021年度: 900千円 (直接経費: 900千円)
2020年度: 800千円 (直接経費: 800千円)
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| キーワード | ジョセフソンパラメトリック増幅器 / マイクロ波 / 超伝導 / パラメトリック増幅 / E-beam lithography / air bridge / three-wave mixing / JTWPA / parametric process / low-loss waveguide / multi-qubit readout / quantum state tomography / parametric amplifier / quantum computing |
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| 研究開始時の研究の概要 |
testDevice design: Review of recent parametric amplifications experiments, Theoretical modeling of device with EM simulations, Device layout preparations with CAD tools
Device fabrication: Fabrication and optimization of device parameters, e.g. junction resistance
Device measurement: Comparison with theoretical model and design verification, Performance test, e.g. gain, noise, Integration with qubit measurement, e.g. quantum tomography
Second iteration of fabrication and measurement: Further design optimization, Studying novel parametric processes and applications
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| 研究実績の概要 |
Throughout this work, we have developed a versatile CAD-assisted circuit design platform and performance estimation tools for designing JTWPAs in different variants, which can reproduce the results of implemented JTWPAs in literatures.
In fabrication, we have been searching for the most suitable Josephson junction design to achieve a high homogeneity in Josephson junction parameters. From the beginning to end of the work, we have reduced the standard deviation (stdev) in junction resistance from over 20% down to 4% in our last measured sample, covering a chip area sufficient for implementing JTWPAs. Our latest junction design to be used in the next batch of JTWPA samples will further reduce the stdev to around 1%, while also greatly improving the junction yield over the previous designs.
From our sample measurements, we have successfully fabricated a low-loss nonlinear transmission line which could act as the basis for JTWPAs. With a comparable electrical length and number of unit cells to JTWPAs in literatures (1413 cells in our sample, comparing to 1000-2000 cells in literatures), we have achieved < 1dB insertion loss comparing to typically 3-6 dB in most other implementations over a similar frequency range. The preliminary measurement results of our samples demonstrated a gain up to an average of 7.5 dB, over a wide bandwidth of 6 GHz. We expect future devices to catch up in terms of gain with more optimized junction and circuit designs.
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| 現在までの達成度 (段落) |
令和4年度が最終年度であるため、記入しない。
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| 今後の研究の推進方策 |
令和4年度が最終年度であるため、記入しない。
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