The two-time Leggett-Garg inequalities of a superconducting qubit interacting with thermal photons in a cavity
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Quantum Physics arXiv:2601.10946 (quant-ph) [Submitted on 16 Jan 2026] Title:The two-time Leggett-Garg inequalities of a superconducting qubit interacting with thermal photons in a cavity Authors:Hiroo Azuma View a PDF of the paper titled The two-time Leggett-Garg inequalities of a superconducting qubit interacting with thermal photons in a cavity, by Hiroo Azuma View PDF HTML (experimental) Abstract:In this paper, we study the two-time Leggett-Garg (LG) inequalities of a quantum optical model that appears in the Josephson-junction quantum bit (qubit) interacting with an external magnetic flux. This model is a natural extension of an exactly solvable model whose interaction between a qubit and single-mode photons is given by a product of the Pauli $z$ operator of the qubit and a linear combination of annihilation and creation operators of the photons. By contrast, a photon's part of the interaction of our model is given by the square of the linear combination. Because our model is not solvable, we approximately investigate its time evolution up to the second-order perturbation. Our numerical calculations show that violation of the LG inequality diminishes as the temperature increases. Moreover, it exhibits power laws of the temperature, whose exponents vary depending on the coupling constant of the interaction between the qubit and photons. The violation of the LG inequality decreases and becomes less sensitive to the temperature as the coupling constant of the interaction gets larger. Comments: Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2601.10946 [quant-ph] (or arXiv:2601.10946v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2601.10946 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Hiroo Azuma [view email] [v1] Fri, 16 Jan 2026 02:23:03 UTC (1,639 KB) Full-text links: Access Paper: View a PDF of the paper titled The two-time Leggett-Garg inequalities of a superconducting qubit interacting with thermal photons in a cavity, by Hiroo AzumaView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-01 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?)