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Control of Superconducting Qubits: Merging Pulse Calibration and System Characterization using Optimal Control

Shai Machnes, Frank K. Wilhelm

Bulletin of the American Physical SocietyMar 7, 20180 citations

High-Speed Calibration and Characterization of Superconducting Quantum Processors without Qubit Reset

M. Werninghaus, D.J. Egger, Stefan Filipp

In order to characterize and calibrate quantum processing devices, a large amount of measurement data has to be collected.Active qubit reset increases the speed at which data can be gathered but requires additional hardware and/or calibration.The experimental apparatus can, however, be operated at elevated repetition rates without reset.In this case, the outcome of a first measurement serves as the initial state for the next experiment.Rol et al. have used this restless operation mode to accelerate the calibration of a single-qubit gate by measuring fixed-length sequences of Clifford gates that compose to X gates [Phys.Rev. Appl.7, 041001 (2017)].However, we find that when measuring pulse sequences that compose to arbitrary operations, distortion appears in the measured data.Here, we extend the restless methodology by showing how to efficiently analyze restless measurements and correct distortions to achieve an identical outcome and accuracy as compared to measurements in which the superconducting qubits are reset.This allows us to rapidly characterize and calibrate qubits.We illustrate this bias-corrected restless measurements method by measuring a Rabi oscillation at a 250 kHz repetition rate without any reset, for a qubit with a decay rate of 1/2π T 1 = 3 kHz.We also show that we can measure a single-and a two-qubit average gate fidelity using randomized benchmarking 20 and 8 times faster, respectively, than measurements that reset the qubits through T 1 decay.In order to characterize and calibrate quantum processing devices, a large amount of measurement data has to be collected.Active qubit reset increases the speed at which data can be gathered but requires additional hardware and/or calibration.The experimental apparatus can, however, be operated at elevated repetition rates without reset.In this case, the outcome of a first measurement serves as the initial state for the next experiment.Rol et al. have used this restless operation mode to accelerate the calibration of a single-qubit gate by measuring fixed-length sequences of Clifford gates that compose to X gates [Phys.Rev. Appl.7, 041001 (2017)].However, we find that when measuring pulse sequences that compose to arbitrary operations, distortion appears in the measured data.Here, we extend the restless methodology by showing how to efficiently analyze restless measurements and correct distortions to achieve an identical outcome and accuracy as compared to measurements in which the superconducting qubits are reset.This allows us to rapidly characterize and calibrate qubits.We illustrate this bias-corrected restless measurements method by measuring a Rabi oscillation at a 250 kHz repetition rate without any reset, for a qubit with a decay rate of 1/2π T 1 = 3 kHz.We also show that we can measure a single-and a two-qubit average gate fidelity using randomized benchmarking 20 and 8 times faster, respectively, than measurements that reset the qubits through T 1 decay.

arXiv:2010.06576PRX QuantumMay 21, 202119 citations

Recent progress in superconducting qubits

Kouichi Semba

IEICE Technical Report; IEICE Tech. Rep.Jan 20, 20060 citations

Optimization of Experimental Setups and Readout for Superconducting Qubits

Taryn V. Stefanski

Feb 1, 20250 citations

Fast Reset Protocol for Superconducting Transmon Qubits

Wei-Ping Yuan, Zhicheng He, Sai Li +1 more

For larger-scale quantum information processing, qubit reset plays an important role, as the coherent times for qubits are limited. However, previous schemes require either long reset times or a complex pulse calibration technique, leading to low efficiency in qubit reset. Here, we propose a fast and simple reset protocol for superconducting transmon qubits based on the coupler-coupled qubits architecture. In this setup, a mixing pulse is used to transfer the qubit excitation to the combined excitation of a low-qulity coupler and readout resonator, which will quickly decay to their respectively ground states, leading to efficient qubit reset to the ground state. Our numerical results show that the residual population of the qubit’s excited state can be suppressed to 0.04% within 28 ns; the reset time will be 283 ns if photon depletion of the readout resonator is required. Thus, our protocol provides a promising way for the high-efficiency superconducting qubit reset.For larger-scale quantum information processing, qubit reset plays an important role, as the coherent times for qubits are limited. However, previous schemes require either long reset times or a complex pulse calibration technique, leading to low efficiency in qubit reset. Here, we propose a fast and simple reset protocol for superconducting transmon qubits based on the coupler-coupled qubits architecture. In this setup, a mixing pulse is used to transfer the qubit excitation to the combined excitation of a low-qulity coupler and readout resonator, which will quickly decay to their respectively ground states, leading to efficient qubit reset to the ground state. Our numerical results show that the residual population of the qubit’s excited state can be suppressed to 0.04% within 28 ns; the reset time will be 283 ns if photon depletion of the readout resonator is required. Thus, our protocol provides a promising way for the high-efficiency superconducting qubit reset.

Applied SciencesJan 6, 20230 citations

Characterisation and optimisation of superconducting qubits

Tyler Jones

Jun 11, 20240 citations

High speed calibration and characterization of superconducting qubits without qubit reset

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