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A cryogen-free dilution refrigerator based Josephson qubit measurement system
1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
The Review of Scientific Instruments
|April 3, 2012
Summary
We developed a cryogen-free dilution refrigerator system for superconducting qubit research. Effective acoustic isolation minimizes coldhead noise, enabling precise measurements of qubit coherence and Josephson junctions.
Area of Science:
- Quantum Computing
- Cryogenic Engineering
- Solid State Physics
Background:
- Cryogen-free dilution refrigerators offer operational advantages for quantum experiments.
- Concerns exist regarding coldhead-induced noise affecting sensitive superconducting qubit measurements.
Purpose of the Study:
- To develop a small-signal measurement system for superconducting qubits using a cryogen-free dilution refrigerator.
- To demonstrate effective acoustic isolation techniques to mitigate coldhead noise.
Main Methods:
- Implementation of a small-signal measurement system within a cryogen-free dilution refrigerator.
- Application of acoustic isolation methods to reduce noise transmission.
- Design of electronic circuits for current, voltage, and microwave lines (DC-100 kHz low-pass).
Main Results:
- Successful characterization of Josephson junction switching current distribution with a 1 nA width.
- Demonstration of high-fidelity superconducting qubit measurements, including Rabi oscillations and Ramsey interference.
Conclusions:
- The developed system is suitable for superconducting qubit studies despite the use of a cryogen-free refrigerator.
- Effective noise reduction strategies enable precise quantum measurements in a more accessible experimental setup.
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