A Cryo-CMOS Controller With Class-DE Driver and DC Magnetic-Field Tuning for Quantum Computers Based on Color Centers in Diamond

• Published in: IEEE journal of solid-state circuits 2024-11, Vol.59 (11), p.3627-3643
• Main Authors: Fakkel, Niels, Enthoven, Luc, Yun, Jiwon, van Riggelen, Margriet, Benjamin van Ommen, Hendrik, Schymik, Kai-Niklas, Bartling, Hans P., Tsapanou Katranara, Eftychia, Vollmer, Rene, Taminiau, Tim H., Babaie, Masoud, Sebastiano, Fabio
• Format: Article
• Language: English
• Subjects: Calibration; class-DE; Coils; Color; cryo-CMOS; DC magnetic field biasing; H-bridge; Larmor frequency; low-power DC current regulator (DC CR); Magnetic fields; microwave driver; nitrogen-vacancy (NV) center; Noise; output stage; Photonics; quantum computing; Qubit; Resonant frequency; resonator; switch-mode amplifier; system engineering; triode
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2024.3459392

Striving toward a scalable quantum processor, this article presents the first cryo-CMOS quantum bit (qubit) controller targeting color centers in diamond. Color-center qubits enable a modular architecture that allows for the 3-D integration of photonics, cryo-CMOS control electronics, and qubits in the same package. However, performing quantum operations in a scalable manner requires large currents in the driving coils due to low coil-to-qubit coupling. Moreover, active calibration of the qubit Larmor frequency is required to compensate inhomogeneities of the bias magnetic field. To overcome these challenges, this work proposes both a cryo-CMOS alternating current (AC) controller consisting of a class-DE series-resonant driver and a DC current regulator (DC CR) that uses a triode-biased H-bridge for scalable low-power qubit operations. By experimentally validating the cryo-CMOS performance with a nitrogen-vacancy (NV) color-center qubit, the AC controller can drive a Rabi oscillation up to 2.5 MHz with a supply draw of 6.5 mA, and the DC CR can tune the Larmor frequency by ±9 MHz while driving up to ±20 mA in the bias coil. T_{2}^{*} coherence times up to 5.3~\mu s and single-qubit gate fidelities above 98% are demonstrated with the cryo-CMOS control using Ramsey experiments and gate set tomography (GST), respectively. The results demonstrate the efficacy of the proposed cryo-CMOS chips and enable the development of a modular quantum processor based on color centers.