Millikelvin temperature cryo-CMOS multiplexer for scalable quantum device characterisation

TL;DR

This paper presents a cryo-CMOS multiplexer operating at millikelvin temperatures, enabling scalable quantum device characterization by reducing the number of necessary signal lines in dilution refrigerators.

Contribution

The authors designed and demonstrated a cryo-CMOS multiplexer functioning at 32 mK with excellent microwave properties, significantly increasing measurement throughput for quantum devices.

Findings

Multiplexer operates effectively up to 10 GHz at 32 mK.

Enabled measurement of four superconducting resonators with a single line.

Facilitates scalable quantum device characterization in large systems.

Abstract

Quantum computers based on solid state qubits have been a subject of rapid development in recent years. In current Noisy Intermediate-Scale Quantum (NISQ) technology, each quantum device is controlled and characterised though a dedicated signal line between room temperature and base temperature of a dilution refrigerator. This approach is not scalable and is currently limiting the development of large-scale quantum system integration and quantum device characterisation. Here we demonstrate a custom designed cryo-CMOS multiplexer operating at 32 mK. The multiplexer exhibits excellent microwave properties up to 10 GHz at room and millikelvin temperatures. We have increased the characterisation throughput with the multiplexer by measuring four high-quality factor superconducting resonators using a single input and output line in a dilution refrigerator. Our work lays the foundation for large-scale microwave quantum device characterisation and has the perspective to address the wiring problem of future large-scale quantum computers.