What is special about the Kirkwood-Dirac distributions?

Quantum Physics arXiv:2511.01996 (quant-ph) [Submitted on 3 Nov 2025] Title:What is special about the Kirkwood-Dirac distributions? Authors:Matéo Spriet, Christopher Langrenez, Raymond Brummelhuis, Stephan De Bièvre View a PDF of the paper titled What is special about the Kirkwood-Dirac distributions?, by Mat\'eo Spriet and 2 other authors View PDF HTML (experimental) Abstract:Among all possible quasiprobability representations of quantum mechanics, the family of Kirkwood-Dirac representations has come to the foreground in recent years because of the flexibility they offer in numerous applications. This raises the question of their characterisation: what makes Kirkwood-Dirac representations special among all possible choices? We show the following. For two observables $\hat A$ and $\hat B$, consider all quasiprobability representations of quantum mechanics defined on the joint spectrum of $\hat A$ and $\hat B$, and that have the correct marginal Born probabilities for $\hat A$ and $\hat B$. For any such Born-compatible quasiprobability representation, we show that there exists, for each observable $\hat{X}$, a naturally associated conditional expectation, given $\hat B$. In addition, among the aforementioned representations, only the Kirkwood-Dirac representation has the following property: its associated conditional expectation of $\hat{X}$ given $\hat{B}$ coincides with the best predictor of $\hat{X}$ by a function of $\hat B$, for all $\hat X$. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2511.01996 [quant-ph] (or arXiv:2511.01996v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2511.01996 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Matéo Spriet [view email] [v1] Mon, 3 Nov 2025 19:11:13 UTC (40 KB) Full-text links: Access Paper: View a PDF of the paper titled What is special about the Kirkwood-Dirac distributions?, by Mat\'eo Spriet and 2 other authorsView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2025-11 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?)