Cryo-CMOS Dual-Qubit Homodyne Reflectometer Array With Degenerate Parametric Amplification

• Published in: IEEE journal of solid-state circuits 2024-10, Vol.59 (10), p.3290-3306
• Main Authors: Geng, Yujie, Lin, Haichuan, Wang, Bo, Wang, Cheng
• Format: Article
• Language: English
• Subjects: Amplification; Arrays; CMOS; Coupled modes; Cryoforming; Cryogenic CMOS (Cryo-CMOS); Cryogenics; degenerate parametric amplifier (DPA); dynamic mode coupling (DMC); Error correction; Gain; High gain; Integrated circuits; Noise; Noise generation; Noise levels; Noise temperature; Parametric amplifiers; Potential oscillations; quantum computer; Quantum computers; quantum state discrimination; Qubit; Qubits (quantum computing); Radio frequency; Reflectometers; Resonators; RF reflectometry; Signal reflection; Signal to noise ratio; Silicon
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2024.3430079

In quantum computers, the quantum state discrimination of the physical quantum bits (Qubits) occupies ~80% of the quantum error correction (QEC) cycle. The RF reflectometry or dispersive readout determines the Qubit state by monitoring the RF reflection of the attached high-Q resonant tank. Compared to their dc counterparts, the RF reflectometers enjoy a high signal-to-noise ratio (SNR), low drifting, and fast speed. As a result, a high-fidelity, single-shot, scalable reflectometer array based on cryogenic CMOS (Cryo-CMOS) ICs is in demand for the future large-scale Qubit array ( 10^{3} {\sim } 10^{6} Qubits). However, the classic Cryo-CMOS heterodyne reflectometers, consisting of MOSFET-based LNA, mixer, and baseband blocks, suffer from high noise temperature and dc power. To address these issues, the Cryo-CMOS parametric circuitry based on varactors is explored. In this article, a dual-Qubit homodyne reflectometer array with 2 RX channels and 1 TX channel is demonstrated. In the RX, the degenerate parametric amplifier (DPA) enjoys a Q-enhanced, \lambda _{\mathrm { RF}}/2 differential-mode (DM) resonator for the high-gain parametric amplification. The common mode (CM) RF input of DPA interacts with the DM resonator by a nonreciprocal, dynamic mode coupling (DMC). It eliminates the necessity of a circulator and the potential oscillation of DPA. The scalability challenge of the DPA's noise temperature T_{\mathrm { noise}} versus the environment temperature T_{\mathrm { env}} is also investigated. In the TX, a current-mode logic (CML) divider with interstate locking and a vector modulator (VM) is implemented to achieve fast modulation for the spur and noise rejection. Measured at 4.2 K, the implemented 65 nm Cryo-CMOS chip presents a 4.5{\sim }7 GHz bandwidth, 52 dB peak RF gain, and 78 K noise temperature, and generates a 10 MHz TX pulse train with -22 dBm RF power and 30 dB tunability. It consumes a total dc power of 33 mW.