Performance of a Kinetic-Inductance Traveling-Wave Parametric Amplifier at 4 Kelvin: Toward an Alternative to Semiconductor Amplifiers

TL;DR

This paper demonstrates a kinetic-inductance traveling-wave parametric amplifier operating at 4 K with low noise and power dissipation, offering a promising alternative to traditional semiconductor amplifiers in quantum computing and sensing.

Contribution

It introduces a KI-TWPA at 4 K with performance comparable to HEMTs but with significantly lower power dissipation, advancing scalable quantum readout technology.

Findings

Chain-added noise of 6.3 K between 3.5 and 5.5 GHz

KI-TWPA's power dissipation is about 1% of a HEMT

Performance limited by input temperature and excess noise

Abstract

Most microwave readout architectures in quantum computing or sensing rely on a semiconductor amplifier at 4 K, typically a high-electron mobility transistor (HEMT). Despite its remarkable noise performance, a conventional HEMT dissipates several milliwatts of power, posing a practical challenge to scale up the number of qubits or sensors addressed in these architectures. As an alternative, we present an amplification chain consisting of a kinetic-inductance traveling-wave parametric amplifier (KI-TWPA) placed at 4 K, followed by a HEMT placed at 70 K, and demonstrate a chain-added noise $T_\Sigma = 6.3\pm0.5$ K between 3.5 and 5.5 GHz. While, in principle, any parametric amplifier can be quantum limited even at 4 K, in practice we find the KI-TWPA's performance limited by the temperature of its inputs, and by an excess of noise $T_\mathrm{ex} = 1.9$ K. The dissipation of the KI-TWPA's rf pump constitutes the main power load at 4 K and is about one percent that of a HEMT. These combined noise and power dissipation values pave the way for the KI-TWPA's use as a replacement for semiconductor amplifiers.