Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow

Quantum Physics arXiv:2608.11314 (quant-ph) [Submitted on 11 Aug 2026] Title:Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow Authors:Chaibata Seida View a PDF of the paper titled Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow, by Chaibata Seida View PDF HTML (experimental) Abstract:A Bell pair distributed through a link that combines amplitude damping with dephasing at time-dependent rates has dynamics that separate into a fixed part and a moving one. The negativity, fully entangled fraction, discord, and average teleportation fidelity depend on time only through the accumulated damping parameters $p(t)$ and $q(t)$. Every threshold is therefore a curve fixed in the unit square, and the rates select nothing but a trajectory across it. The Horodecki fidelity formula $\bar{F} = \frac{1}{2} + \frac{1}{6}\mathrm{Tr}|T|$ covers one- and two-sided exposure alike: the condition $\det T \leq 0$ under which it takes this form holds throughout the unit square for both. Under symmetric two-sided noise the entanglement vanishes when $p+q\geq1$, where the exact relation $\bar{F}^{2s}=\frac{2}{3}+\frac{1}{3}\mathcal{N}_{2s}$ ties disentanglement and the loss of quantum advantage to the same instant. One-sided exposure admits no finite-time sudden death for any rate profile, and the discord stays strictly positive throughout the open square, so the distributed state can be separable, useless for teleportation, and still nonclassical. For harmonically modulated rates, complete positivity caps the backflow at one modulation period of static decay, $\Delta\Gamma_{k}\leq2\pi\gamma_{k,0}/\Omega$, equivalently at a modulation depth $\xi_{k}\leq4.6033$ independent of $\Omega$. Inside that window the trajectory reverses, producing finite intervals of restored quantum advantage and entanglement sudden birth. Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2608.11314 [quant-ph] (or arXiv:2608.11314v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2608.11314 Focus to learn more arXiv-issued DOI via DataCite (pending registration) Submission history From: Chaibata Seida [view email] [v1] Tue, 11 Aug 2026 18:03:16 UTC (229 KB) Full-text links: Access Paper: View a PDF of the paper titled Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow, by Chaibata SeidaView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2026-08 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?) 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?)