Advanced Concepts in Josephson Junction Reflection Amplifiers

TL;DR

This paper discusses the development and analysis of Josephson junction-based microwave amplifiers aiming to approach the quantum noise limit, including experimental results and design challenges.

Contribution

It introduces a novel amplifier based on intrinsic negative resistance of a selectively damped Josephson junction and explores flux-pumped metamaterial amplifiers with wide tunability.

Findings

Demonstrated wide-band microwave amplification near quantum limit

Studied flux-pumped metamaterial amplifiers with tunable frequency

Identified challenges for improving existing Josephson junction amplifier designs

Abstract

Low-noise amplification atmicrowave frequencies has become increasingly important for the research related to superconducting qubits and nanoelectromechanical systems. The fundamental limit of added noise by a phase-preserving amplifier is the standard quantum limit, often expressed as noise temperature $T_{q} = \hbar {\omega}/2k_{B}$. Towards the goal of the quantum limit, we have developed an amplifier based on intrinsic negative resistance of a selectively damped Josephson junction. Here we present measurement results on previously proposed wide-band microwave amplification and discuss the challenges for improvements on the existing designs. We have also studied flux-pumped metamaterial-based parametric amplifiers, whose operating frequency can be widely tuned by external DC-flux, and demonstrate operation at $2\omega$ pumping, in contrast to the typical metamaterial amplifiers pumped via signal lines at $\omega$.