Fragmentation of Virtual Orbitals for Quantum Computing: Reducing Qubit Requirements through Many-Body Expansion

Quantum Physics arXiv:2510.20950 (quant-ph) [Submitted on 23 Oct 2025] Title:Fragmentation of Virtual Orbitals for Quantum Computing: Reducing Qubit Requirements through Many-Body Expansion Authors:Federico Zahariev, Mark S. Gordon View a PDF of the paper titled Fragmentation of Virtual Orbitals for Quantum Computing: Reducing Qubit Requirements through Many-Body Expansion, by Federico Zahariev and Mark S. Gordon View PDF HTML (experimental) Abstract:The development of quantum computing for molecular simulations is constrained by the limited number of qubits available on current Noisy Intermediate-Scale Quantum (NISQ) devices. The present work introduces the Virtual Orbital Fragmentation (FVO) method, a systematic approach that reduces qubit requirements by 40--66\% while maintaining chemical accuracy. The method partitions the virtual orbital space into chemically intuitive fragments and employs many-body expansion techniques analogous to spatial fragmentation methods. Applications to six molecular systems demonstrate that the 2-body FVO expansion achieves errors below 3 kcal/mol, while the 3-body expansion provides sub-kcal/mol accuracy. When integrated with the Variational Quantum Eigensolver (VQE) and combined with the Effective Fragment Molecular Orbital (EFMO) method for multi-molecular systems, the hierarchical Q-EFMO-FVO approach achieves 96--100\% accuracy relative to full calculations. The method provides a practical pathway for quantum chemical calculations on current 50--100 qubit processors and establishes virtual orbital fragmentation as a complementary strategy to spatial fragmentation for managing quantum computational complexity. Subjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph) Cite as: arXiv:2510.20950 [quant-ph] (or arXiv:2510.20950v1 [quant-ph] for this version) https://doi.org/10.48550/arXiv.2510.20950 Focus to learn more arXiv-issued DOI via DataCite Submission history From: Federico Zahariev Dr. [view email] [v1] Thu, 23 Oct 2025 19:22:59 UTC (875 KB) Full-text links: Access Paper: View a PDF of the paper titled Fragmentation of Virtual Orbitals for Quantum Computing: Reducing Qubit Requirements through Many-Body Expansion, by Federico Zahariev and Mark S. GordonView PDFHTML (experimental)TeX Source view license Current browse context: quant-ph new | recent | 2025-10 Change to browse by: physics physics.chem-ph 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?)