Broadband SNAIL parametric amplifier with microstrip impedance transformer

Abstract

Josephson parametric amplifiers are an important part of a modern superconducting quantum computing platform and squeezed quantum states generation devices. Traveling 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 67 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 one e-beam lithography step.

Improving Josephson junction reproducibility for superconducting quantum circuits: junction area fluctuation

“…Coherence and frequency masurements are presented in Table 1 . Next, we fabricated and tested a SNAIL parametric amplifier with 25 SNAIL cells and large asymmetry 38 . The areas of 0.63 μm 2 and 0.055 μm 2 for large and small junctions respectively were used (α = 0.087) to obtain the frequency of 6 GHz.…”