Time-domain characterization and correction of on-chip distortion of control pulses in a quantum processor

• Published in: Applied physics letters Vol. 116; no. 5
• Main Authors: Rol, M. A., Ciorciaro, L., Malinowski, F. K., Tarasinski, B. M., Sagastizabal, R. E., Bultink, C. C., Salathe, Y., Haandbaek, N., Sedivy, J., DiCarlo, L.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 03-02-2020
• Subjects: Applied physics; Cryoscopy; Digital filters; Distortion; Gates (circuits); Microprocessors; Quantum electrodynamics; Qubits (quantum computing); Room temperature; Step response; Temporal resolution; Waveform generators; Waveforms
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5133894

We introduce Cryoscope, a method for sampling on-chip baseband pulses used to dynamically control qubit frequency in a quantum processor. We specifically use Cryoscope to measure the step response of the dedicated flux control lines of two-junction transmon qubits in circuit QED processors with the temporal resolution of the room-temperature arbitrary waveform generator producing the control pulses. As a first application, we iteratively improve this step response using optimized real-time digital filters to counter the linear-dynamical distortion in the control line, as needed for high-fidelity repeatable one- and two-qubit gates based on dynamical control of qubit frequency.