Cryogenic Multiplexing Control Chip for a Superconducting Quantum Processor

This paper proposes a scheme and design of a cryogenic multiplexing control chip (MCC), which enables one microwave cable to control many superconducting qubits. Designed based on an adjustable inductor, the MCC is a nonreciprocal device that generates microwave signals between 4 and 8 GHz and constructs a XY control circuit to operate qubits. The effects of filters, isolators, power splitters, qubits, and load impedance on the MCC are analyzed in the frequency-domain simulation. And in the time-domain simulation, the response time, Gaussian pulses, single sideband, amplitude, and frequency compensation of the MCC are examined. The MCC can be integrated with the superconducting qubits on the same package at the 20-mK temperature stage with insertion loss of -6 dB and isolation of -26 dB. The timedomain simulation has revealed that the output specific microwave pulses of the MCC can be used for driving the superconducting qubits with crosstalk of about -80 dB. This is much less than -40 dB of the physical requirements on crosstalk, which can meet fidelity on single-qubit (99.92%) and two-qubit gates (99.40%). The power dissipation for each qubit control is less than 1 pW. The MCC can greatly reduce the number of microwave control lines and is beneficial to the development of a large-scale superconducting quantum processor.