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Crosstalk characterization in superconducting qubits by eigenvalue estimation: Experiment

Matthew Ware, Kin Chung Fong, Colm A. Ryan +3 more

Bulletin of the American Physical SocietyMar 14, 20160 citations

Measuring and quantifying classical crosstalk in multi-qubit superconducting circuits

Petar Jurcevic, Abhinav Kandala, Antonio D. Corcoles +3 more

Bulletin of the American Physical SocietyMar 4, 20190 citations

Characterization and Implications of Low Frequency Noise in Superconducting Flux Qubit Circuits

R. Therrien, Dale J. Van Harlingen, Timothy L. Robertson +5 more

APSMar 1, 20020 citations

Suppression of Qubit Crosstalk in a Tunable Coupling Superconducting Circuit Device

Pranav Mundada, Gengyan Zhang, Andrew Houck

Bulletin of the American Physical SocietyMar 7, 20180 citations

Characterization of tunable coupler without a dedicated readout resonator in superconducting circuits

Chi Zhang, Tian-Le Wang, Liang-Liang Guo +6 more

Tunable couplers have recently emerged as an essential component in superconducting quantum processors. These couplers usually do not have readout resonators to save control or hardware overhead; this makes it challenging to characterize and calibrate the coupler, which will undoubtedly limit the performance of a fast two-qubit gate. Here, we theoretically demonstrate that by mapping the coupler's state onto that of its neighboring qubit, the high-contrast readout of the coupler can be realized. We experimentally implement such a readout scheme with a single-shot readout fidelity of 86%, which is mainly limited by the thermal population of our sample. We further demonstrate how to calibrate the flux crosstalk related to the coupler and its flux distortion that are ignored in the previous works. These calibration steps are imperative for realizing robust and accurate quantum operations in frequency-tunable superconducting circuits.Tunable couplers have recently emerged as an essential component in superconducting quantum processors. These couplers usually do not have readout resonators to save control or hardware overhead; this makes it challenging to characterize and calibrate the coupler, which will undoubtedly limit the performance of a fast two-qubit gate. Here, we theoretically demonstrate that by mapping the coupler's state onto that of its neighboring qubit, the high-contrast readout of the coupler can be realized. We experimentally implement such a readout scheme with a single-shot readout fidelity of 86%, which is mainly limited by the thermal population of our sample. We further demonstrate how to calibrate the flux crosstalk related to the coupler and its flux distortion that are ignored in the previous works. These calibration steps are imperative for realizing robust and accurate quantum operations in frequency-tunable superconducting circuits.

Applied Physics LettersJan 9, 202311 citations

Inherent flux crosstalk and coupler-driven single-qubit gates in superconducting circuits

Anonymous, Guido Burkard

Crosstalk refers to unwanted qubit addressing. This is particularly detrimental when scaling up quantum information systems because unintended interactions limit their overall performance. For superconducting qubits, tunable couplings and frequency tunability achieved through externally applied magnetic fluxes enable high-fidelity entangling gates; however, they also introduce crosstalk through unintended flux coupling. In this work, we investigate the impact of time-dependent external magnetic fluxes in quantized circuits on superconducting qubit couplings. We find that nontrivial cross-voltage driving emerges between capacitively linked qubits when the magnetic flux threading the superconducting loop of a qubit varies in time, in a manner analogous to Faraday’s law of induction. Crucially, we show that this effect enables fast single-qubit control through the coupler element in standard tunable-coupler architectures, potentially eliminating the need for individual microwave X Y control lines.Crosstalk refers to unwanted qubit addressing. This is particularly detrimental when scaling up quantum information systems because unintended interactions limit their overall performance. For superconducting qubits, tunable couplings and frequency tunability achieved through externally applied magnetic fluxes enable high-fidelity entangling gates; however, they also introduce crosstalk through unintended flux coupling. In this work, we investigate the impact of time-dependent external magnetic fluxes in quantized circuits on superconducting qubit couplings. We find that nontrivial cross-voltage driving emerges between capacitively linked qubits when the magnetic flux threading the superconducting loop of a qubit varies in time, in a manner analogous to Faraday’s law of induction. Crucially, we show that this effect enables fast single-qubit control through the coupler element in standard tunable-coupler architectures, potentially eliminating the need for individual microwave X Y control lines.

Physical Review AppliedSep 21, 20260 citations

Fast and accurate flux-crosstalk characterization in superconducting-qubit circuits

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