Selective Single and Double-Mode Quantum Limited Amplifier

TL;DR

This paper introduces a superconducting kinetic inductance-based quantum-limited amplifier operable at higher temperatures and magnetic fields, surpassing Josephson junction amplifiers in power handling and tunability for quantum computing and sensing.

Contribution

The authors develop and experimentally demonstrate a novel kinetic inductance amplifier that operates at higher temperatures, with tunable single and double-mode amplification, and improved power handling over traditional Josephson junction amplifiers.

Findings

Achieves over 50 dB gain in single-mode and 32 dB in double-mode.

Operates effectively up to 4.5 K, higher than typical Josephson-based amplifiers.

Maintains low noise addition of 0.35 quanta near the quantum limit.

Abstract

A quantum-limited amplifier enables the amplification of weak signals while introducing minimal noise dictated by the principles of quantum mechanics. These amplifiers serve a broad spectrum of applications in quantum computing, including fast and accurate readout of superconducting qubits and spins, as well as various uses in quantum sensing and metrology. Parametric amplification, primarily developed using Josephson junctions, has evolved into the leading technology for highly effective microwave measurements within quantum circuits. Despite their significant contributions, these amplifiers face fundamental limitations, such as their inability to handle high powers, sensitivity to parasitic magnetic fields, and particularly their limitation to operate only at millikelvin temperatures. To tackle these challenges, here we experimentally develop a novel quantum-limited amplifier based on superconducting kinetic inductance and present an extensive theoretical model to describe this nonlinear coupled-mode system. Our device surpasses the conventional constraints associated with Josephson junction amplifiers by operating at much higher temperatures up to 4.5 K. With two distinct spectral modes and tunability through bias current, this amplifier can operate selectively in both single and double-mode amplification regimes near the quantum noise limit. Utilizing a nonlinear thin film exhibiting kinetic inductance, our device attains gain exceeding 50 dB in a single-mode and 32 dB in a double-mode configuration while adding 0.35 input-referred quanta of noise. Importantly, this amplifier eliminates the need for Josephson junctions, resulting in significantly higher power handling capabilities than Josephson-based amplifiers. It also demonstrates resilience in the presence of magnetic fields, offers a straightforward design, and enhances reliability.