Event - 30 August 2023

Multiplexed superconducting qubit control with ultra-low-power cryo-CMOS multiplexer operating below 20 mK

Lectured by Rohith Acharya


A large-scale superconducting quantum computing system will require the control and readout of a large number of high-fidelity qubits operating at millikelvin temperatures. CMOS based cryo-electronics offer a scalable solution to overcome the input-output bottleneck present in these systems. The high throughput required for quantum processors can be achieved using a network of multiplexers and de-multiplexers at the base temperature stage of a dilution refrigerator. As the multiplexers are intended to operate in close proximity to the qubits, the electronic and thermal noise generated during their operation could be detrimental to the qubit performance. In this work, we present the electrical characterization results obtained for a custom-designed RF multiplexer operating at 20 mK with an ultra-low static power consumption of ~0.7 mW. We benchmark its performance by interfacing it with a superconducting qubit and observe that the qubit’s relaxation times are unaffected, while the coherence times are marginally affected in both static and dynamic operation. Using the multiplexer, single qubit gate fidelities above 99.9% — that is, above the threshold for surface-code based quantum error-correction — can be achieved with appropriate thermal filtering. Our results pave the way for the integration of cryo-CMOS based multiplexers at the base temperature of the dilution refrigerator for addressing multiple quantum devices and enabling large-scale device characterization.

[1] Rohith Acharya et al. “Overcoming I/O Bottleneck in Superconducting Quantum Computing: Multiplexed Qubit Control with Ultra-Low-Power, Base-Temperature Cryo-CMOS Multiplexer.” arXiv preprint arXiv:2209.13060 (2022).
[2] Rohith Acharya et al. “Scalable 1.4 ΜW Cryo-CMOS SP4T Multiplexer Operating at 10 MK for High-Fidelity Superconducting Qubit Measurements.” In 2022 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits), 230–31 (2022).


30/8/2023 14:00 - 15:00