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 to large-scale superconducting quantum processors. The module delivers a voltage range of ±7 V with 200 mA maximum current per channel, while achieving the following key performance benchmarks: noise spectral density of 20 nV/ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msqrt> <mml:mrow> <mml:mi mathvariant="normal">Hz</mml:mi> </mml:mrow> </mml:msqrt> </mml:mrow> </mml:math> at 10 kHz, output ripple &lt;500 μV pp within 20 MHz bandwidth, and long-term voltage drift &lt;5 μV pp over 12 hours. Integrated into the control electronics of a 66-qubit quantum processor, QPower enables qubit coherence time of T 1 = 87.6 μs and Ramsey dephasing time of T 2 = 5.1 μs, with qubit resonance frequency drift constrained to ±40 kHz during 12-hour operation. This modular design is compact in size and efficient in energy consumption, providing a scalable DC source solution for intermediate-scale quantum processors with stringent noise and stability requirements, with potential extensions to other quantum hardware platforms and precision measurement systems.