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Nonreciprocal Microwave Signal Processing with a Field-Programmable Josephson Amplifier
F Lecocq1, L Ranzani2, G A Peterson1
1National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA.
Physical Review Applied
|March 19, 2024
Summary
We developed a field-programmable Josephson amplifier (FPJA), a versatile superconducting circuit. This compact device enables flexible frequency conversion and amplification for quantum technologies.
Area of Science:
- Superconducting circuits
- Quantum electronics
- Microwave engineering
Background:
- Superconducting circuits are crucial for quantum computing and sensitive measurements.
- Existing amplifiers often lack flexibility and require complex operating conditions.
Purpose of the Study:
- To design and implement a novel field-programmable Josephson amplifier (FPJA).
- To demonstrate the FPJA's capability for various microwave signal processing functions.
- To assess its performance and suitability for integration with quantum systems.
Main Methods:
- Utilized a gradiometric superconducting quantum-interference device (SQUID) with Nb/Al-AlOx/Nb Josephson junctions.
- Programmed the FPJA *in situ* using microwave drives.
- Tested four distinct operational modes: frequency conversion, circulation, phase-preserving amplification, and directional phase-preserving amplification.
Main Results:
- Achieved -0.5 dB transmission and -30 dB reflection for frequency conversion and circulation.
- Demonstrated phase-preserving amplification with >20 dB gain and 1 photon of added noise.
- Showcased directional phase-preserving amplification with 18 dB forward gain and 8 dB reverse isolation.
- Observed quantitative agreement between experimental results and theoretical predictions.
Conclusions:
- The FPJA is a compact, lossless, and programmable superconducting circuit.
- It offers flexible reciprocal and nonreciprocal operations with high performance.
- Its design is insensitive to flux noise and operates without magnetic shielding, facilitating on-chip integration with quantum circuits.
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