Errors in quantum tomography: diagnosing systematic versus statistical errors

A prime goal of quantum tomography is to provide quantitatively rigorous characterization of quantum systems, be they states, processes or measurements, particularly for the purposes of trouble-shooting and benchmarking experiments in quantum information science. A range of techniques exist to enabl...

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Main Author: Nathan K Langford
Format: Article
Language:English
Published: IOP Publishing 2013-01-01
Series:New Journal of Physics
Online Access:https://doi.org/10.1088/1367-2630/15/3/035003
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author Nathan K Langford
author_facet Nathan K Langford
author_sort Nathan K Langford
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description A prime goal of quantum tomography is to provide quantitatively rigorous characterization of quantum systems, be they states, processes or measurements, particularly for the purposes of trouble-shooting and benchmarking experiments in quantum information science. A range of techniques exist to enable the calculation of errors, such as Monte-Carlo simulations, but their quantitative value is arguably fundamentally flawed without an equally rigorous way of authenticating the quality of a reconstruction to ensure it provides a reasonable representation of the data, given the known noise sources. A key motivation for developing such a tool is to enable experimentalists to rigorously diagnose the presence of technical noise in their tomographic data. In this work, I explore the performance of the chi-squared goodness-of-fit test statistic as a measure of reconstruction quality. I show that its behaviour deviates noticeably from expectations for states lying near the boundaries of physical state space, severely undermining its usefulness as a quantitative tool precisely in the region which is of most interest in quantum information processing tasks. I suggest a simple, heuristic approach to compensate for these effects and present numerical simulations showing that this approach provides substantially improved performance.
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spelling doaj.art-36436f3841d145c289e6f9b2d6cd22a22023-08-08T11:08:27ZengIOP PublishingNew Journal of Physics1367-26302013-01-0115303500310.1088/1367-2630/15/3/035003Errors in quantum tomography: diagnosing systematic versus statistical errorsNathan K Langford0Department of Physics, Royal Holloway University of London , Egham, Surrey TW20 0EX, UKA prime goal of quantum tomography is to provide quantitatively rigorous characterization of quantum systems, be they states, processes or measurements, particularly for the purposes of trouble-shooting and benchmarking experiments in quantum information science. A range of techniques exist to enable the calculation of errors, such as Monte-Carlo simulations, but their quantitative value is arguably fundamentally flawed without an equally rigorous way of authenticating the quality of a reconstruction to ensure it provides a reasonable representation of the data, given the known noise sources. A key motivation for developing such a tool is to enable experimentalists to rigorously diagnose the presence of technical noise in their tomographic data. In this work, I explore the performance of the chi-squared goodness-of-fit test statistic as a measure of reconstruction quality. I show that its behaviour deviates noticeably from expectations for states lying near the boundaries of physical state space, severely undermining its usefulness as a quantitative tool precisely in the region which is of most interest in quantum information processing tasks. I suggest a simple, heuristic approach to compensate for these effects and present numerical simulations showing that this approach provides substantially improved performance.https://doi.org/10.1088/1367-2630/15/3/035003
spellingShingle Nathan K Langford
Errors in quantum tomography: diagnosing systematic versus statistical errors
New Journal of Physics
title Errors in quantum tomography: diagnosing systematic versus statistical errors
title_full Errors in quantum tomography: diagnosing systematic versus statistical errors
title_fullStr Errors in quantum tomography: diagnosing systematic versus statistical errors
title_full_unstemmed Errors in quantum tomography: diagnosing systematic versus statistical errors
title_short Errors in quantum tomography: diagnosing systematic versus statistical errors
title_sort errors in quantum tomography diagnosing systematic versus statistical errors
url https://doi.org/10.1088/1367-2630/15/3/035003
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