A Low-noise And High-stability DC Source For Superconducting Quantum Circuits

Abstract

With the rapid scaling of superconducting quantum processors, electronic control systems relying on commercial off-the-shelf instruments face critical bottlenecks in signal density, power consumption, and crosstalk mitigation. Here we present a custom dual-channel direct current (DC) source module (QPower) dedicated for large-scale superconducting quantum processors. The module delivers a voltage range of $\pm$7 V with 200 mA maximum current per channel, while achieving the following key performance benchmarks: noise spectral density of 20 nV/$\sqrt{\{}\{Hz\}\}$ at 10 kHz, output ripple $<$500 $\mu$V${}_{\{}\{pp\}\}$ within 20 MHz bandwidth, and long-term voltage drift $<$5 $\mu$V${}_{\{}\{pp\}\}$ over 12 hours. Integrated into the control electronics of a 66-qubit quantum processor, QPower enables qubit coherence times of $T_1=87.6\mu \{s\}$ and Ramsey $T_2=5.1\mu \{s\}$, with qubit resonance frequency drift constrained to $\pm$40 kHz