Broadband SNAIL parametric amplifier with microstrip impedance transformer

TL;DR

This paper introduces a broadband, quantum-limited SNAIL-based parametric amplifier with impedance matching, achieving high gain, wide bandwidth, and high saturation power suitable for quantum information processing.

Contribution

The authors develop a microstrip impedance transformer and an array of SNAILs to enhance bandwidth and dynamic range in a superconducting parametric amplifier, with simple fabrication.

Findings

Achieves 17 dB gain over 300 MHz bandwidth

Demonstrates quantum-limited noise performance

Operates with a broad tunable frequency range

Abstract

Josephson parametric amplifiers have emerged as a promising platform for quantum information processing and squeezed quantum states generation. Travelling wave and impedance-matched parametric amplifiers provide broad bandwidth for high-fidelity single-shot readout of multiple qubit superconducting circuits. Here, we present a quantum-limited 3-wave-mixing parametric amplifier based on superconducting nonlinear asymmetric inductive elements (SNAILs), whose useful bandwidth is enhanced with an on-chip two-section impedance-matching circuit based on microstrip transmission lines. The amplifier dynamic range is increased using an array of sixty-seven SNAILs with 268 Josephson junctions, forming a nonlinear quarter-wave resonator. Operating in a current-pumped mode, we experimentally demonstrate an average gain of $17 dB$ across $300 MHz$ bandwidth, along with an average saturation power of $- 100 dBm$, which can go as high as $- 97 dBm$ with quantum-limited noise performance. Moreover, the amplifier can be fabricated using a simple technology with just a one e-beam lithography step. Its central frequency is tuned over a several hundred megahertz, which in turn broadens the effective operational bandwidth to around $1.5 GHz$.