Benchmarking the quality of multiplexed qubit readout beyond assignment fidelity

Fuente: arXiv
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Main Authors: Di Giovanni, Andras, Aasen, Adrian Skasberg, Lisenfeld, Jürgen, Gärttner, Martin, Rotzinger, Hannes, Ustinov, Alexey V.
Format: Preprint
Published: 2025
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author Di Giovanni, Andras
Aasen, Adrian Skasberg
Lisenfeld, Jürgen
Gärttner, Martin
Rotzinger, Hannes
Ustinov, Alexey V.
author_facet Di Giovanni, Andras
Aasen, Adrian Skasberg
Lisenfeld, Jürgen
Gärttner, Martin
Rotzinger, Hannes
Ustinov, Alexey V.
contents The accurate measurement of quantum two-level objects (qubits) is crucial for developing quantum computers. Over the last decade, the measure of choice for benchmarking readout routines for superconducting qubits has been assignment fidelity. However, this method only focuses on the preparation of computational basis states and therefore does not provide a complete characterization of the readout. Here, we expand the focus to the use of detector tomography to fully characterize multiqubit readout of superconducting transmon qubits. The impact of different readout parameters on the rate of information extraction is studied using quantum state reconstruction infidelity as a proxy. The results are then compared with assignment fidelities, showing good agreement for separable two-qubit states. We therefore propose the rate of infidelity convergence as a validation tool for assignment fidelity and a more comprehensive benchmark for single- and multiqubit readout optimization. To make the best use of experimental resources, we investigate the most efficient distribution of a limited shot budget between detector tomography and state reconstruction within the context of single- and two-qubit experiments. To address the growing interest in three-qubit gates and test scalability of the validation tool, we perform three-qubit quantum state tomography that goes beyond conventional readout-error-mitigation methods and find a factor of 30 reduction in quantum infidelity. Our results demonstrate that qubit readout correlations are not induced by a significantly reduced state distinguishability. Consequently, correlation coefficients can serve as a valuable tool in qubit readout optimization.
format Preprint
id arxiv_https___arxiv_org_abs_2502_08589
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Benchmarking the quality of multiplexed qubit readout beyond assignment fidelity
Di Giovanni, Andras
Aasen, Adrian Skasberg
Lisenfeld, Jürgen
Gärttner, Martin
Rotzinger, Hannes
Ustinov, Alexey V.
Quantum Physics
Superconductivity
The accurate measurement of quantum two-level objects (qubits) is crucial for developing quantum computers. Over the last decade, the measure of choice for benchmarking readout routines for superconducting qubits has been assignment fidelity. However, this method only focuses on the preparation of computational basis states and therefore does not provide a complete characterization of the readout. Here, we expand the focus to the use of detector tomography to fully characterize multiqubit readout of superconducting transmon qubits. The impact of different readout parameters on the rate of information extraction is studied using quantum state reconstruction infidelity as a proxy. The results are then compared with assignment fidelities, showing good agreement for separable two-qubit states. We therefore propose the rate of infidelity convergence as a validation tool for assignment fidelity and a more comprehensive benchmark for single- and multiqubit readout optimization. To make the best use of experimental resources, we investigate the most efficient distribution of a limited shot budget between detector tomography and state reconstruction within the context of single- and two-qubit experiments. To address the growing interest in three-qubit gates and test scalability of the validation tool, we perform three-qubit quantum state tomography that goes beyond conventional readout-error-mitigation methods and find a factor of 30 reduction in quantum infidelity. Our results demonstrate that qubit readout correlations are not induced by a significantly reduced state distinguishability. Consequently, correlation coefficients can serve as a valuable tool in qubit readout optimization.
title Benchmarking the quality of multiplexed qubit readout beyond assignment fidelity
topic Quantum Physics
Superconductivity
url https://arxiv.org/abs/2502.08589