{"paper":{"title":"Comparative assessment of germanium-based spin-qubit modalities: donor, acceptor, gate-defined hole, and gate-defined electron platforms","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Gate-defined germanium hole-spin qubits currently lead in electrical controllability, multiqubit demonstrations, and scalability potential compared to donor, acceptor, and electron variants.","cross_cats":[],"primary_cat":"quant-ph","authors_text":"A. Prem, D.-M. Mei, K.-M. Dong, N. Budhathoki, S. A. Panamaldeniya, S. Bhattarai, S. Chhetri","submitted_at":"2026-05-13T15:38:36Z","abstract_excerpt":"High-purity germanium (Ge) has re-emerged as a versatile semiconductor platform for spin-based quantum information processing because it combines mature materials processing, access to spin-free isotopes, high mobilities, small effective masses, and strong but engineerable spin--orbit coupling. However, ``Ge qubits'' are not a single technology. Donor spin qubits, acceptor spin qubits, gate-defined hole spin qubits, and gate-defined electron spin qubits exploit different parts of the Ge band structure and therefore make distinct trade-offs among coherence, controllability, fabrication complexi"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"gate-defined Ge hole-spin qubits currently offer the strongest combination of all-electrical control, demonstrated multiqubit operation, and scalability.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The literature values and demonstrated results for each modality are representative and comparable on a common footing; the calibrated reference relaxation rate and geometry-dependent suppression factor in the T1 framework accurately capture real devices without unaccounted parasitic channels.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Gate-defined hole spin qubits in germanium currently combine the best all-electrical control, demonstrated multiqubit operation, and scalability path among the four modalities compared.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Gate-defined germanium hole-spin qubits currently lead in electrical controllability, multiqubit demonstrations, and scalability potential compared to donor, acceptor, and electron variants.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"f58ee001ae6264f964d26963c7f767bf6fa49a1e6f735bb673bdc124967ca142"},"source":{"id":"2605.13680","kind":"arxiv","version":1},"verdict":{"id":"95ab78e5-8202-4de0-b914-2f0232088cef","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-14T18:25:17.839444Z","strongest_claim":"gate-defined Ge hole-spin qubits currently offer the strongest combination of all-electrical control, demonstrated multiqubit operation, and scalability.","one_line_summary":"Gate-defined hole spin qubits in germanium currently combine the best all-electrical control, demonstrated multiqubit operation, and scalability path among the four modalities compared.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The literature values and demonstrated results for each modality are representative and comparable on a common footing; the calibrated reference relaxation rate and geometry-dependent suppression factor in the T1 framework accurately capture real devices without unaccounted parasitic channels.","pith_extraction_headline":"Gate-defined germanium hole-spin qubits currently lead in electrical controllability, multiqubit demonstrations, and scalability potential compared to donor, acceptor, and electron variants."},"references":{"count":51,"sample":[{"doi":"","year":2025,"title":"Quantum error correction below the surface code threshold.Nature, 638(8052):920–926, 2025","work_id":"54b631ba-5995-478d-a744-9ea70ee1dbe3","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2019,"title":"Jeroen P. G. van Dijk, Edoardo Charbon, and Fabio Sebastiano. The electronic interface for quantum processors.Microprocessors and Microsystems, 66:90–101, 2019","work_id":"40baca0f-7319-4430-aa4e-6a4daddd5f29","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2021,"title":"Zwanenburg, Daniel Loss, Maksym My- ronov, Jian-Jun Zhang, Silvano De Franceschi, Georgios Katsaros, and Menno Veldhorst","work_id":"5b9c5fd9-78d5-49a1-8bc2-9b387750d6dc","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2021,"title":"L. A. Terrazos, E. Marcellina, Z. Wang, S. N. Coppersmith, M. Friesen, A. R. Hamilton, X. Hu, B. Koiller, A. L. Saraiva, R. B. Capaz, and D. Culcer. Theory of hole-spin qubits in strained germanium qu","work_id":"9cc05aef-e7c6-42eb-aefe-b69a282a59f0","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2021,"title":"Zhanning Wang, Elizabeth Marcellina, Alex. R. Hamilton, James H. Cullen, Sven Rogge, Joe Salfi, and Dimitrie Culcer. Optimal operation points for ultrafast, highly coherent Ge hole spin-orbit qubits.n","work_id":"33a23ef1-ccae-4309-8ad0-18fb21f4ba5a","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":51,"snapshot_sha256":"97f1aebce2cfbb81b541cb3e667f58e5e9090e3c1b6524b8d2e6905401f454b3","internal_anchors":1},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}