| Project/Area Number |
23K20871
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| Project/Area Number (Other) |
21H01134 (2021-2023)
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Multi-year Fund (2024)
Single-year Grants (2021-2023) |
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| Section | 一般 |
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| Review Section |
Basic Section 16010:Astronomy-related
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| Research Institution | National Astronomical Observatory of Japan |
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Principal Investigator |
SHAN Wenlei 国立天文台, 先端技術センター, 准教授 (60792570)
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| Co-Investigator(Kenkyū-buntansha) |
江崎 翔平 国立天文台, 先端技術センター, 研究技師 (40794508)
田村 友範 国立天文台, 先端技術センター, 技師 (90897828)
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| Project Period (FY) |
2021-04-01 – 2026-03-31
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| Project Status |
Granted (Fiscal Year 2024)
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| Budget Amount *help |
¥17,030,000 (Direct Cost: ¥13,100,000、Indirect Cost: ¥3,930,000)
Fiscal Year 2025: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2024: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2023: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2022: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2021: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
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| Keywords | Focal plane array / SIS mixer / Radio astronomy / planar OMT / Focal Plane Array / Heterodyne / SIS Mixer / Radio Astronomy |
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| Outline of Research at the Start |
This research is relevant to a new technological approach to constructing sub-mm heterodyne focal plane arrays for radioastronomical observation. This approach is characterized by the adoption of superconducting monolithic microwave integrated circuits (MMICs) and hybrid planar integration (HPI) schemes.
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| Outline of Annual Research Achievements |
In FY 2023, we concentrated on investigating losses in superconducting thin-film transmission lines, which serve as the backbone of MMIC SIS mixers currently under development. This study addresses the fundamental differences between MMIC SIS mixers and traditional SIS mixers based on quartz substrates.
In silicon-based MMIC SIS mixers, longer superconducting transmission lines (around five wavelengths) are necessary to accommodate more complex circuits, including orthomode transducers and sideband separation circuits. This introduces transmission loss as a significant factor, potentially degrading the sensitivity of SIS mixers.Despite the importance of transmission loss in superconducting transmission lines operating at millimeter and sub-millimeter wavelengths, experimental studies are limited due to technical challenges. To address this gap, we developed two methods for assessing the superconducting thin-film transmission lines:On-Chip Detectors: This method integrates detectors directly onto the chip, enabling in-situ measurements;Network Analyzer: This approach utilizes a network analyzer to measure the transmission loss across the superconducting lines.Both methods have yielded significant results, contributing valuable insights into the superconducting transmission lines' performance. These findings are essential to achieving the project's research goals and advancing the development of MMIC SIS mixers.
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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
The research plan for the fiscal year 2023 focused on advancing MMIC technology through four key tasks:
(1)Transmission Loss Investigation: It was fully fulfilled with significant progress made in transmission measurement methods for superconducting microstrips and coplanar waveguides at 2 mm wavelengths and liquid helium temperatures. The following major results were obtained: The measured transmission loss cannot be attributed solely to conduction loss produced by normal electrons;The dielectric loss in amorphous materials is significantly higher than in bulk materials, likely due to two-level system loss;Radiation loss can become significant when the size of the coplanar waveguide exceeds a small fraction of the wavelength;Magnetic fields applied perpendicularly to superconducting thin films can lead to notable loss, explained by vortex flow.
(2)MMIC Fabrication Process: We conducted a series of tests to optimize the photolithography system, enhancing control over line widths to dimensions around 1 micrometer.(3)Crosstalk Mitigation: We redesigned the mixer holder to minimize the stimulation of undesired modes causing crosstalk. An existing mixer holder has been modified and is awaiting experimental confirmation.(4)Sideband Separation Demonstration: This task intended to complete the demonstration of the sideband separation configuration with silicon-based MMICs at ALMA Band 4. However, due to a focus on Task 1, this work was suspended and will be reassigned in FY 2024.
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| Strategy for Future Research Activity |
The following studies will be performed in the 2024 fiscal year:(1) Conclude the results obtained in the investigation of the transmission loss of planar superconducting transmission lines by publishing research papers. Reconsider the design and fabrication process of MMIC SIS mixer based on these results and try to improve the sensitivity. (2) Continue studies on the fabrication process of MMICs to improve the fabrication yield and the quality of SIS junctions in terms of the nonlinearity of the IV characteristics. (3) Finish the experimental verification of the alternative method to TSVs to solve the crosstalk problem. (4) Finally, complete the demonstration of sideband separation configuration with silicon-based MMICs at ALMA Band 4.
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