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Applied Physics Letters

Impedance matched Josephson parametric amplifier with a multisection λ/4 transmission line transformer

Tianshi Zhou, Wenqu Xu, Quan Zuo, Jiazheng Pan, Zishuo Li, Kaixuan Zhang, Tingting Guo, Yifan Sheng, Lingxiao Jing, Huashi Ma, Mingyuan Yu, Sining Zhou, Binglin Li, Shiyao Yang, Yongyang Yu, Jiyuan Zhu, Junzhou Zhang, Jinpeng Li, Chunhai Cao, Guozhu Sun, Peiheng Wu

Published Mar 1, 2025• 5 citations
Publisher

Abstract

We report the fabrication and characterization of an impedance matched Josephson parametric amplifier (IMPA). A multisection λ/4 transmission line transformer (TLT) is utilized, which can reduce the input impedance and provide a wide impedance matched bandwidth. In addition, the whole IMPA device is fabricated on a LaAlO3 substrate with a dielectric constant of 23.4, much larger compared to the commonly used intrinsic silicon substrate, to provide larger grounded capacitance, making the fabrication of the multisection λ/4 TLT more precise and reliable. The experimental results show that by adjusting the working point, the amplifier has a bandwidth of 580 MHz with a gain of more than 15 dB. The average input saturation power is about −115 dBm within the bandwidth. Additionally, its noise performance is close to the quantum-limited level.

DOI
10.1063/5.0250918

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We report the fabrication and characterization of an impedance matched Josephson parametric amplifier (IMPA). A multisection λ/4 transmission line transformer (TLT) is utilized, which can reduce the input impedance and provide a wide impedance matched bandwidth. In addition, the whole IMPA device is fabricated on a LaAlO3 substrate with a dielectric constant of 23.4, much larger compared to the commonly used intrinsic silicon substrate, to provide larger grounded capacitance, making the fabrication of the multisection λ/4 TLT more precise and reliable. The experimental results show that by adjusting the working point, the amplifier has a bandwidth of 580 MHz with a gain of more than 15 dB. The average input saturation power is about −115 dBm within the bandwidth. Additionally, its noise performance is close to the quantum-limited level.
An impedance matched parametric amplifier (IMPA) with Josephson junctions is fabricated and characterized. A hybrid structure containing coplanar and strip structures is implemented to realize an impedance taper line and a plate capacitor in an LC nonlinear resonator based on Josephson junctions. The upper plate of the capacitor is isolated with SiN x without grounding as well as the strips. Such easily-prepared designs greatly reduce the requirements for lithography alignment and precision, which makes the fabrication process more reliable. The experimental results show that in such IMPA a gain higher than 25 dB with a bandwidth of about 100 MHz can be obtained. This broadband amplifier operates close to the quantum limit. By adjusting the working point, a higher bandwidth of about 400 MHz can be obtained with a gain of about 17 dB.
In this paper, we introduce a method of using a double-layer resist lift-off process to prepare the capacitor dielectric layer for fabricating impedance-engineered Josephson parametric amplifiers (IMPAs). Compared to prior art, this method enhances fabrication success rate and accelerates production. The IMPA we made, experimentally achieves an instantaneous bandwidth over 950 (600) MHz with a gain exceeding 10 (14) dB, along with saturation input power of −115 dBm and near quantum-limited noise. We demonstrate the negligible backaction from the IMPA on superconducting qubits, resulting in no significant degradation of the relaxation time and coherence time of the qubits. The IMPA improves the signal-to-noise ratio from 1.69 to 14.56 and enables the amplification chain to achieve high quantum efficiency with η ≈ 0.26, making it a critical necessity for large-scale quantum computation.
We describe a wide-band Josephson Parametric Amplifier (JPA) that is impedance-matched using an integrated compact superconducting transmission line transformer. The impedance transformer consists of two broadside coupled transmission lines configured in a Ruthroff topology which enables a wide matching bandwidth from 2 to 18GHz, reducing the input line impedance and the device resonance quality factor by a factor of 4. This enables gain flatness and flexibility in the choice of the amplifier’s tuning range. The amplifier has up to 20dB gain, with less than 1dB of ripple, 2-3GHz gain-bandwidth product and -126dBm input 1-dB compression point. Moreover, the device active area fits into a 1mm×1mm space, thus easing integration into large quantum systems.
Quantum-limited Josephson parametric amplifiers play a pivotal role in advancing the field of circuit quantum electrodynamics by enabling the fast and high-fidelity measurement of weak microwave signals. Therefore, it is necessary to develop robust parametric amplifiers with low noise, broad bandwidth, and reduced design complexity for microwave detection. However, current broadband parametric amplifiers either have degraded noise performance or rely on complex designs. Here, we present a device based on the broadband impedance-transformed Josephson parametric amplifier that integrates a hornlike coplanar waveguide transmission line, which significantly decreases the design and fabrication complexity while keeping comparable performance. The device shows an instantaneous bandwidth of 700 (200) MHz for 15 (20) dB gain with an average input saturation power of −110 dBm and near quantum-limited added noise. The operating frequency can be tuned over 1.4 GHz using an external flux bias. We further demonstrate the negligible backaction from our device on a transmon qubit. The amplification performance and simplicity of our device promise its wide adaptation in quantum metrology, quantum communication, and quantum information processing. Published by the American Physical Society 2024
We present a fishbone-like lumped-element artificial transmission line to overcome impedance mismatch in a reflection-type Josephson parametric amplifier between a nonlinear resonator and an external transmission line. Using this easily prepared architecture, we design and fabricate a broadband Josephson parametric amplifier, which has gain in an excess of 20 dB with a bandwidth of hundreds of MHz. Furthermore, by varying the working point of the device, the operating frequency of amplification can be tuned in a wide frequency range of 1 GHz while the amplifier operates in the mode of either three-wave mixing or four-wave mixing. Such a parametric amplifier is suitable for engineering applications of superconducting circuit quantum electrodynamics.
We present an impedance engineered Josephson parametric amplifier capable of providing bandwidth beyond the traditional gain-bandwidth product. We achieve this by introducing a positive linear slope in the imaginary component of the input impedance seen by the Josephson oscillator using a λ/2 transformer. Our theoretical model predicts an extremely flat gain profile with a bandwidth enhancement proportional to the square root of amplitude gain. We experimentally demonstrate a nearly flat 20 dB gain over a 640 MHz band, along with a mean 1-dB compression point of −110 dBm and near quantum-limited noise. The results are in a good agreement with our theoretical model.