{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2026:CKVMIHUWCH5KICPSLB5H5HYS26","short_pith_number":"pith:CKVMIHUW","schema_version":"1.0","canonical_sha256":"12aac41e9611faa409f2587a7e9f12d79d615c5394e9a2d8bc89d0798e570dda","source":{"kind":"arxiv","id":"2605.14586","version":1},"attestation_state":"computed","paper":{"title":"Fraxonium: Fractional fluxon states for qudit encoding","license":"http://creativecommons.org/licenses/by/4.0/","headline":"A superconducting circuit generalizes the fluxonium using fractional fluxon states for protected qudit encoding.","cross_cats":["cond-mat.mes-hall"],"primary_cat":"quant-ph","authors_text":"Gianluigi Catelani, Luca Chirolli, Luigi Amico, Uri Vool, Valentina Brosco","submitted_at":"2026-05-14T08:58:07Z","abstract_excerpt":"We propose a superconducting circuit hosting $d$ low-lying states, well separated from the rest of the spectrum, that naturally realizes a qudit system protected from leakage errors. The system represents a generalization of the fluxonium and the low-energy states are constituted by fractional fluxon states, that we call {\\it fraxons}, localized in the minima of a suitably designed Josephson potential. The latter is tailored through a Fourier engineering approach, that employs multi-harmonic Josephson building block elements composed by a Josephson junction and an inductance connected in serie"},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":true,"formal_links_present":false},"canonical_record":{"source":{"id":"2605.14586","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"quant-ph","submitted_at":"2026-05-14T08:58:07Z","cross_cats_sorted":["cond-mat.mes-hall"],"title_canon_sha256":"4037bf72e185d244d638ca22ffc2b61450b2a22f9c477da0acfb113cdc563e81","abstract_canon_sha256":"c353e7a8c9d968ee2a78cd82b5d1db63d99f811af94f29fbb16752d74336a849"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:39:05.307455Z","signature_b64":"wLsQLpOo5VKsUQxxaduRs5ThkNo5YU3x66GMYGRpbXo+C284WYKiHQD5ta9+Uf2giWyZi1GzR6zGE3je7EXuCg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"12aac41e9611faa409f2587a7e9f12d79d615c5394e9a2d8bc89d0798e570dda","last_reissued_at":"2026-05-17T23:39:05.306737Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:39:05.306737Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Fraxonium: Fractional fluxon states for qudit encoding","license":"http://creativecommons.org/licenses/by/4.0/","headline":"A superconducting circuit generalizes the fluxonium using fractional fluxon states for protected qudit encoding.","cross_cats":["cond-mat.mes-hall"],"primary_cat":"quant-ph","authors_text":"Gianluigi Catelani, Luca Chirolli, Luigi Amico, Uri Vool, Valentina Brosco","submitted_at":"2026-05-14T08:58:07Z","abstract_excerpt":"We propose a superconducting circuit hosting $d$ low-lying states, well separated from the rest of the spectrum, that naturally realizes a qudit system protected from leakage errors. The system represents a generalization of the fluxonium and the low-energy states are constituted by fractional fluxon states, that we call {\\it fraxons}, localized in the minima of a suitably designed Josephson potential. The latter is tailored through a Fourier engineering approach, that employs multi-harmonic Josephson building block elements composed by a Josephson junction and an inductance connected in serie"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"The system represents a generalization of the fluxonium and the low-energy states are constituted by fractional fluxon states, that we call fraxons, localized in the minima of a suitably designed Josephson potential.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"A suitably designed Josephson potential can be realized through Fourier engineering with multi-harmonic elements such that d low-lying fractional fluxon states remain well separated from the rest of the spectrum.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Superconducting circuit hosts fractional fluxon states (fraxons) in a tailored Josephson potential to realize protected qudits with a STIRAP gate protocol.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"A superconducting circuit generalizes the fluxonium using fractional fluxon states for protected qudit encoding.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"936dfee4c0b3b4d4d83afbb20acdf8f2363ee81032f490972e9627aeea41f65e"},"source":{"id":"2605.14586","kind":"arxiv","version":1},"verdict":{"id":"5a704302-43b2-4c69-b60e-0db74a8fc489","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T01:24:42.507682Z","strongest_claim":"The system represents a generalization of the fluxonium and the low-energy states are constituted by fractional fluxon states, that we call fraxons, localized in the minima of a suitably designed Josephson potential.","one_line_summary":"Superconducting circuit hosts fractional fluxon states (fraxons) in a tailored Josephson potential to realize protected qudits with a STIRAP gate protocol.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"A suitably designed Josephson potential can be realized through Fourier engineering with multi-harmonic elements such that d low-lying fractional fluxon states remain well separated from the rest of the spectrum.","pith_extraction_headline":"A superconducting circuit generalizes the fluxonium using fractional fluxon states for protected qudit encoding."},"references":{"count":146,"sample":[{"doi":"","year":null,"title":"All the branches are connected in parallel, with a fluxπ/2 between the four equal modular elements","work_id":"4d975859-aa59-4315-b96b-362289808875","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2023,"title":"Ω3Ω#=Ω Ω3 |2⟩|1⟩|0⟩ |𝑢⟩ Ω!Ω#Ω","work_id":"c2719d32-1108-47ec-ba98-07c8ad6e59fd","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":null,"title":"Tight-binding model Following [107], we can model the dynamics between the fluxon states localized in the minima of the effective transmon potential through a tight-binding approach. The fluxon states","work_id":"a72c6e95-d1ed-4c75-ac0e-f2a339a09dbe","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":null,"title":"cos[φx −π(m−n)/2] −E J Dmn( √ 2σ) cos[2φx −π(m−n)/2],(D4) In the working regimeE J ≫E C, EL, the level spacing provided by √8ECEL is small compared toE J and a large number of Fock states is needed to","work_id":"ac87b359-1a18-42e8-a6f3-85e60a4b6949","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1995,"title":"P. W. Shor, Scheme for reducing decoherence in quan- tum computer memory, Phys. Rev. A52, R2493 (1995)","work_id":"ade9b5a3-b3e9-4d29-886a-cee4bc3325f5","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":146,"snapshot_sha256":"9fb5bcce2519513482c7f6995ac7d004b1d2348a1c221b8ea955b80c12f65a52","internal_anchors":2},"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"},"aliases":[{"alias_kind":"arxiv","alias_value":"2605.14586","created_at":"2026-05-17T23:39:05.306844+00:00"},{"alias_kind":"arxiv_version","alias_value":"2605.14586v1","created_at":"2026-05-17T23:39:05.306844+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2605.14586","created_at":"2026-05-17T23:39:05.306844+00:00"},{"alias_kind":"pith_short_12","alias_value":"CKVMIHUWCH5K","created_at":"2026-05-18T12:33:37.589309+00:00"},{"alias_kind":"pith_short_16","alias_value":"CKVMIHUWCH5KICPS","created_at":"2026-05-18T12:33:37.589309+00:00"},{"alias_kind":"pith_short_8","alias_value":"CKVMIHUW","created_at":"2026-05-18T12:33:37.589309+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26","json":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26.json","graph_json":"https://pith.science/api/pith-number/CKVMIHUWCH5KICPSLB5H5HYS26/graph.json","events_json":"https://pith.science/api/pith-number/CKVMIHUWCH5KICPSLB5H5HYS26/events.json","paper":"https://pith.science/paper/CKVMIHUW"},"agent_actions":{"view_html":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26","download_json":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26.json","view_paper":"https://pith.science/paper/CKVMIHUW","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=2605.14586&json=true","fetch_graph":"https://pith.science/api/pith-number/CKVMIHUWCH5KICPSLB5H5HYS26/graph.json","fetch_events":"https://pith.science/api/pith-number/CKVMIHUWCH5KICPSLB5H5HYS26/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26/action/timestamp_anchor","attest_storage":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26/action/storage_attestation","attest_author":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26/action/author_attestation","sign_citation":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26/action/citation_signature","submit_replication":"https://pith.science/pith/CKVMIHUWCH5KICPSLB5H5HYS26/action/replication_record"}},"created_at":"2026-05-17T23:39:05.306844+00:00","updated_at":"2026-05-17T23:39:05.306844+00:00"}