# Multiplexed quantum transport using commercial off-the-shelf CMOS at sub-kelvin temperatures

## TL;DR

This paper demonstrates multiplexed quantum transport at sub-kelvin temperatures using commercial CMOS technology, significantly increasing measurement throughput and advancing silicon qubit array development.

## Contribution

It introduces a CMOS-based multiplexing approach for quantum transport measurements at cryogenic temperatures, enabling higher throughput and improved material quality for quantum computing.

## Key findings

- Achieved an order of magnitude increase in measurement channels.
- Recorded record electron mobility in industrial CMOS-fabricated wafers.
- Demonstrated potential for scalable quantum device characterization.

## Abstract

Continuing advancements in quantum information processing have caused a paradigm shift from research mainly focused on testing the reality of quantum mechanics to engineering qubit devices with numbers required for practical quantum computation. One of the major challenges in scaling toward large-scale solid-state systems is the limited input/output (I/O) connectors present in cryostats operating at sub-kelvin temperatures required to execute quantum logic with high-fidelity. This interconnect bottleneck is equally present in the device fabrication-measurement cycle, which requires high-throughput and cryogenic characterization to develop quantum processors. Here we multiplex quantum transport of two-dimensional electron gases at sub-kelvin temperatures. We use commercial off-the-shelf CMOS multiplexers to achieve an order of magnitude increase in the number of wires. Exploiting this technology we advance 300 mm epitaxial wafers manufactured in an industrial CMOS fab to a record electron mobility of (3.9$\pm$0.6)$\times$10$^5$ cm$^2$\slash Vs and percolation density of (6.9$\pm$0.4)$\times$10$^{10}$ cm$^{-2}$, representing a key step toward large silicon qubit arrays. We envision that the demonstration will inspire the development of cryogenic electronics for quantum information and because of the simplicity of assembly, low-cost, yet versatility, we foresee widespread use of similar cryo-CMOS circuits for high-throughput quantum measurements and control of quantum engineered systems.