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Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing

arXiv Quantum Physics
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A team led by Emanuel Knill introduces rigorous fidelity bounds for broadband pulsed (BBP) homodyne measurements, generalizing standard pulsed homodyne techniques to leverage high-efficiency detectors like calorimeters. The study quantifies how closely BBP and standard homodyne measurements approximate ideal quadrature measurements, showing convergence depends on local oscillator amplitude and photon number moments. Lower bounds are derived for post-measurement state fidelity, including both measurement outcomes and unmeasured modes, critical for error mitigation in continuous-variable quantum systems. Practical applications are demonstrated in quantum teleportation, Wigner function estimation, and GKP code error correction, validating the bounds’ relevance for near-term quantum computing. The work bridges theoretical limits with experimental feasibility, offering tools to optimize homodyne detection for scalable continuous-variable quantum information processing.
Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing

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Quantum Physics arXiv:2602.22511 (quant-ph) [Submitted on 26 Feb 2026] Title:Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing Authors:Emanuel Knill, Ezad Shojaee, James R. van Meter, Akira Kyle, Scott Glancy View a PDF of the paper titled Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing, by Emanuel Knill and 4 other authors View PDF Abstract:In arXiv:2503.00188 we introduced broadband pulsed (BBP) homodyne measurements as a generalization of standard pulsed homodyne quadrature measurements. BBP can take advantage of detectors such as calorimeters that have the potential for high efficiency over a broad spectral range. BBP homodyne retains the advantages of standard pulsed homodyne, enabling measurement of arbitrary quadratures in the limit of large amplitude local oscillators (LO). Here we quantify the convergence of standard and BBP homodyne quadrature measurements to those of the quadrature of interest. We obtain lower bounds on the fidelity of the post-measurement classical-quantum state of outcomes and unmeasured modes, and the fidelity of the states obtained after applying operations conditional on measurement outcomes. The bounds depend on the LO amplitude and the moments of number operators. We demonstrate the practical relevance of these bounds by evaluating them for standard pulsed homodyne used for estimating values of the characteristic function of the Wigner distribution, expectations of moments, for quantum teleportation and for continuous variable error correction with GKP codes. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2602.22511 [quant-ph] (or arXiv:2602.22511v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2602.22511 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Emanuel Knill [view email] [v1] Thu, 26 Feb 2026 01:04:10 UTC (152 KB) Full-text links: Access Paper: View a PDF of the paper titled Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing, by Emanuel Knill and 4 other authorsView PDFTeX Source view license Current browse context: quant-ph new | recent | 2026-02 References & Citations INSPIRE HEP NASA ADSGoogle Scholar Semantic Scholar export BibTeX citation Loading... BibTeX formatted citation × loading... Data provided by: Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv (What is alphaXiv?) Links to Code Toggle CatalyzeX Code Finder for Papers (What is CatalyzeX?) DagsHub Toggle DagsHub (What is DagsHub?) GotitPub Toggle Gotit.pub (What is GotitPub?) Huggingface Toggle Hugging Face (What is Huggingface?) Links to Code Toggle Papers with Code (What is Papers with Code?) ScienceCast Toggle ScienceCast (What is ScienceCast?) Demos Demos Replicate Toggle Replicate (What is Replicate?) Spaces Toggle Hugging Face Spaces (What is Spaces?) Spaces Toggle TXYZ.AI (What is TXYZ.AI?) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower (What are Influence Flowers?) Core recommender toggle CORE Recommender (What is CORE?) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs. Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)

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Source: arXiv Quantum Physics