# A photonic crystal Josephson traveling wave parametric amplifier

## TL;DR

This paper introduces a compact, tunable, and near-quantum-limited traveling wave parametric amplifier based on superconducting quantum interference devices with a photonic crystal-inspired design, suitable for quantum technologies.

## Contribution

It presents a novel superconducting Josephson traveling wave amplifier with a photonic crystal-inspired dispersion engineering, achieving high bandwidth, low noise, and simplified fabrication.

## Key findings

- 3 GHz bandwidth achieved
- -102 dBm 1-dB compression point
- Added noise near the quantum limit

## Abstract

An amplifier combining noise performances as close as possible to the quantum limit with large bandwidth and high saturation power is highly desirable for many solid state quantum technologies such as high fidelity qubit readout or high sensitivity electron spin resonance for example. Here we introduce a new Traveling Wave Parametric Amplifier based on Superconducting QUantum Interference Devices. It displays a 3 GHz bandwidth, a -102 dBm 1-dB compression point and added noise near the quantum limit. Compared to previous state-of-the-art, it is an order of magnitude more compact, its characteristic impedance is in-situ tunable and its fabrication process requires only two lithography steps. The key is the engineering of a gap in the dispersion relation of the transmission line. This is obtained using a periodic modulation of the SQUID size, similarly to what is done with photonic crystals. Moreover, we provide a new theoretical treatment to describe the non-trivial interplay between non-linearity and such periodicity. Our approach provides a path to co-integration with other quantum devices such as qubits given the low footprint and easy fabrication of our amplifier.