A C-Band Cryogenic GaAs MMIC Low-Noise Amplifier for Quantum Applications

TL;DR

This paper introduces a cryogenic C-Band GaAs MMIC low-noise amplifier designed for quantum computing readout, achieving high gain and low noise at 3.6 K, and demonstrating effective qubit measurement without quantum-limited amplifiers.

Contribution

It presents a novel GaAs-based cryo-LNA with integrated feedback and biasing, optimized for quantum applications, and benchmarks its performance with superconducting qubits.

Findings

Achieves 40 dB gain and 5 K noise temperature at 3.6 K

Demonstrates 98.3% single-shot readout fidelity

Operates with low power consumption of 15 mW

Abstract

Large-scale superconducting quantum computers require massive numbers of high-performance cryogenic low-noise amplifiers (cryo-LNA) for qubit readout. Here we present a C-Band monolithic microwave integrated circuit (MMIC) cryo-LNA for this purpose. This cryo-LNA is based on 150 nm GaAs pseudomorphic high electron mobility transistor (pHEMT) process and implemented with a three-stage cascaded architecture, where the first stage adopts careful impedance match to optimize the noise and return loss. The integration of negative feedback loops adopted in the second and third-stage enhances the overall stability. Moreover, the pHEMT-self bias and current multiplexing circuitry structure facilitate the reduction of power consumption and require only single bias line. Operating at an ambient temperature of 3.6 K and consuming 15 mW, the cryo-LNA demonstrates good performance in the C-band, reaching a 5 K equivalent noise temperature and an average gain of 40 dB. We further benchmark this cryo-LNA with superconducting qubits, achieving an average single-shot dispersive readout fidelity of 98.3% without assistance from a quantum-limited parametric amplifier. The development of GaAs cryo-LNA diversifies technical support necessary for large-scale quantum applications.