A Cryogenic Front-end Module Apply to Readout Two-qubits with FDM Technology in Superconducting Quantum Computing System

A massive quantum bits (qubits) array is required to mitigate gate error rates in order to realize a practical quantum computing system. An integrated broadband front-end module is employed for the readout of two transmon qubits using frequency division multiplexing (FDM) technology. The front-end module features a customized IQ up-conversion mixer, fabricated using a 28-nm CMOS process, supporting an RF range of 4–10 GHz with a conversion gain of 0.3 ± 3 dB at 4 K. It achieves sufficient linearity with third-order intermodulation distortion (IM3) exceeding 45 dB and exhibits image rejection ratio (IRR) and LO rejection ratio (LORR) of 57 dB and 50 dB, respectively. The functionality of the front-end module is validated through the successful readout of two qubits. A readout fidelity of around 80% is measured, consistent with the baseline result.