論文ID: 2024CTI0001
Silicon spin qubits are a promising technology for scalable quantum computing, leveraging their inherent compatibility with CMOS integration process. However, as the number of silicon spin qubits increases, the exponential growth in signal cables required to control qubits within a dilution refrigerator become a significant bottleneck, along with the thermal inflow from external control systems. In addition, the implementation of signal wiring for qubit chips with a large number of I/O pads and internal heat generation of qubits themselves are also barriers to scale-up. To address these issues, we have developed cryogenic CMOS (Cryo-CMOS) analog circuits and advanced chip packaging techniques at deep cryogenic temperatures inside the refrigerator. These techniques enable the implementation of extensive signal wiring while suppressing heat generation, contributing to the realization of large-scale silicon spin qubit control. In this paper, we introduce cryogenic analog circuit designs including digital-to-analog converter (DAC) and analog-to-digital converter (ADC) for biasing spin qubits and acquiring their environmental data, respectively, with a focus on low power consumption and small area to meet space and power budget within the refrigerator. Furthermore, we introduce cryogenic flip-chip packaging techniques using silicon interposer and Cu-Cu bonding technology to enhance heat dissipation as examples of packaging strategies for installing large-scale qubit chips. These proposed techniques have been implemented as prototype chips, and their effectiveness has been demonstrated through cryogenic experiments using refrigerators.
