Characterizing Coherent Errors using Matrix-Element Amplification
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866917932884295680 |
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| author | Gross, Jonathan A. Genois, Elie Debroy, Dripto M. Zhang, Yaxing Mruczkiewicz, Wojciech Cian, Ze-Pei Jiang, Zhang |
| author_facet | Gross, Jonathan A. Genois, Elie Debroy, Dripto M. Zhang, Yaxing Mruczkiewicz, Wojciech Cian, Ze-Pei Jiang, Zhang |
| contents | Repeating a gate sequence multiple times amplifies systematic errors coherently, making it a useful tool for characterizing quantum gates. However, the precision of such an approach is limited by low-frequency noises, while its efficiency hindered by time-consuming scans required to match up the phases of the off-diagonal matrix elements being amplified. Here, we overcome both challenges by interleaving the gate of interest with dynamical decoupling sequences in a protocol we call Matrix-Element Amplification using Dynamical Decoupling (MEADD). Using frequency-tunable superconducting qubits from a Google Sycamore quantum processor, we experimentally demonstrate that MEADD surpasses the accuracy and precision of existing characterization protocols for estimating systematic errors in single- and two-qubit gates. In particular, MEADD yields factors of 5 to 10 improvements in estimating coherent parameters of the $\mathrm{CZ}$ gates compared to existing methods, reaching a precision below one milliradian. We also use it to characterize coherent crosstalk in the processor which was previously too small to detect reliably. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_12550 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Characterizing Coherent Errors using Matrix-Element Amplification Gross, Jonathan A. Genois, Elie Debroy, Dripto M. Zhang, Yaxing Mruczkiewicz, Wojciech Cian, Ze-Pei Jiang, Zhang Quantum Physics Repeating a gate sequence multiple times amplifies systematic errors coherently, making it a useful tool for characterizing quantum gates. However, the precision of such an approach is limited by low-frequency noises, while its efficiency hindered by time-consuming scans required to match up the phases of the off-diagonal matrix elements being amplified. Here, we overcome both challenges by interleaving the gate of interest with dynamical decoupling sequences in a protocol we call Matrix-Element Amplification using Dynamical Decoupling (MEADD). Using frequency-tunable superconducting qubits from a Google Sycamore quantum processor, we experimentally demonstrate that MEADD surpasses the accuracy and precision of existing characterization protocols for estimating systematic errors in single- and two-qubit gates. In particular, MEADD yields factors of 5 to 10 improvements in estimating coherent parameters of the $\mathrm{CZ}$ gates compared to existing methods, reaching a precision below one milliradian. We also use it to characterize coherent crosstalk in the processor which was previously too small to detect reliably. |
| title | Characterizing Coherent Errors using Matrix-Element Amplification |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2404.12550 |