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As the qubit number increases, the complexity of wiring becomes bottleneck for realizing a large-scale universal quantum computer due to the increased heat load generated through those wires and the induced noise, reducing the qubit fidelity. To resolve the wiring issue for large-scale quantum computers, we propose cryo-CMOS system-on-a-chips (SOCs) to drive and read out both superconducting and semiconductor qubits. The qubit control circuits including digital, digital/analog interface, and RF frontend modules will be designed and operated at 4 K. For the readout, we will demonstrate a gate reflectometry including low-noise amplifiers (LNAs) and analog-to-digital converters (ADCs) combined with a cryo-FPGA at ~ 20 mK to 4 K to reduce the distance between the LNA and qubits. To further improve the transmission quality, we propose a novel idea to replace coaxial cables with optical links, where signals are generated by vertical-cavity surface-emitting lasers (VCSELs).
NTUEE team is working on cryo-CMOS circuits and system to control (arbitrary waveform) solid-state qubits and signal readout (sinusoidal waveform). The cryo-CMOS chips are placed at temperature of 4 K (pink) to control the qubits at a mK (blue) regime.
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Co-PI
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Liang-Hung Lu (National Taiwan University)
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Shih-Yuan Chen (National Taiwan University)
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Chia-Hsiang Yang (National Taiwan University)
Cryo-CMOS Control and Readout of Solid-State Qubits
We design cryo-CMOS system-on-a-chips (SOCs) to access solid-state qubits to resolve issues of heating, noise, unreasonable cost due to wiring. This project includes control modules, such as digital, digital-to-analog interface, and RF frontend circuits, and use gate reflectrometry including low-noise amplifiers, analog-to-digital converter and FPGA circuits for qubit readout. We now achieve a 30-GHz VCO for signal generation and high-quality LNA circuit for readout. Other circuit blocks are under testing and will be used for qubit control and readout in the next phase.
The figure shows the CMOS circuits for control and readout of semiconductor or superconducting qubits, including digital, analog, and RF circuit modules.