For superconducting quantum processors, microwave signals are delivered to each qubit from room-temperature electronics to the cryogenic environment through coaxial cables. Limited by the heat load of cabling and the massive cost of electronics, such an architecture is not viable for millions of qubits required for fault-tolerant quantum computing. Monolithic integration of the control electronics and the qubits provides a promising solution, which, however, requires a coherent cryogenic microwave pulse generator that is compatible with superconducting quantum circuits. Here, we report such a signal source driven by digital-like signals, generating pulsed microwave emission with well-controlled phase, intensity, and frequency directly at millikelvin temperatures. We showcase high-fidelity readout of superconducting qubits with the microwave pulse generator. The device demonstrated here has a small footprint, negligible heat load, great flexibility to operate, and is fully compatible with today's superconducting quantum circuits, thus providing an enabling technology for large-scale superconducting quantum computers.
@article{arxiv.2407.11775,
title = {A cryogenic on-chip microwave pulse generator for large-scale superconducting quantum computing},
author = {Zenghui Bao and Yan Li and Zhiling Wang and Jiahui Wang and Jize Yang and Haonan Xiong and Yipu Song and Yukai Wu and Hongyi Zhang and Luming Duan},
journal= {arXiv preprint arXiv:2407.11775},
year = {2024}
}