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Digital Control of Superconducting Qubit Using a Josephson Pulse Generator at 3K



Logan Howe, Manuel Castellanos Beltran, Adam Sirois, David Olaya, John Biesecker, Paul Dresselhaus, Samuel P. Benz, Pete Hopkins


Scaling of quantum computers to fault-tolerant levels relies critically on the integration of energy-efficient, stable, and reproducible qubit control and readout electronics. In comparison to traditional semiconductor-control electronics (TSCE) located at room temperature, the signals generated by rf sources based on Josephson-junctions (JJs) benefit from small device sizes, low power dissipation, intrinsic calibration, superior reproducibility, and insensitivity to ambient fluctuations. Previous experiments to colocate qubits and JJ-based control electronics have resulted in quasiparticle poisoning of the qubit, degrading the coherence and lifetime of the qubit. In this paper, we digitally control a 0.01-K transmon qubit with pulses from a Josephson pulse generator (JPG) located at the 3-K stage of a dilution refrigerator. We directly compare the qubit lifetime T1, the coherence time T∗2 , and the thermal occupation Pth when the qubit is controlled by the JPG circuit versus the TSCE setup. We find agreement to within the daily fluctuations of ±0.5 μs and ±2 μs for T1 and T∗2 , respectively, and agreement to within the 1% error for Pth. Additionally, we perform randomized benchmarking to measure an average JPG gate error of 2.1 × 10−2. In combination with a small device size (< 25 mm2) and low on-chip power dissipation ( 100 μW), these results are an important step toward demonstrating the viability of using JJ-based control electronics located at temperature stages higher than the mixing-chamber stage in highly scaled superconducting quantum information systems.
PRX Quantum


Quantum computing, scalable, cryogenic control, Josephson junction (JJ), Single Flux Quantum (SFQ), qubit, transmon, superconductor, voltage metrology


Howe, L. , Castellanos Beltran, M. , Sirois, A. , Olaya, D. , Biesecker, J. , Dresselhaus, P. , Benz, S. and Hopkins, P. (2022), Digital Control of Superconducting Qubit Using a Josephson Pulse Generator at 3K, PRX Quantum, [online],, (Accessed April 17, 2024)
Created March 25, 2022, Updated November 29, 2022