{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"3edd26c61452b333de382a56c6b38cf783f5a40803c45fb2a209a14f5d453a5d","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"aed1750af93705db37f0483481937f9927a75d8150832a39f42779fbc9b13c71","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"amo.optical-clocks-second.solid-state-nuclear-clock","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Thorium-229 nuclei embedded in a transparent crystal can be laser-excited, which could make a clock that is compact and insensitive to many disturbances. The crystal environment broadens and shifts the line, and the ultimate accuracy is unknown.","posed_since":"","precise":"For Th-229 in CaF2, LiSrAlF6 or ThF4 hosts, identify the mechanisms (temperature-dependent electric-field gradients, inhomogeneous broadening from charge-compensating defects, isomer quenching by radiation-induced defects) limiting linewidth and frequency reproducibility, and determine the achievable fractional uncertainty of a solid-state nuclear clock.","problem_ref":null,"references":"","settled_by":"Repeated measurements across crystals and temperatures with a closed-loop nuclear clock compared to an optical clock, giving a reproducibility budget below 1e-17.","status_note":"Temperature sensitivity was measured in 2024, crystal-to-crystal reproducibility in 2025, and a Th-229 nuclear clock with feedback loop was reported in June 2026.","title":"What limits the accuracy of a solid-state thorium nuclear clock?","topic_ref":"5d572b616becc2d77dc7833412720dbdbc6e7e6aa45f95467fa95e2923acf321"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"1c75c8063c36a7d6c08cdba885f650c4cc05bacbdb506ada402b318843a6fa7c","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bc871b65377f5e0c190790ae6726be03dbf657f5777eb30271815286b42e1d44","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"xmlIwhEHq1WaszvqiEKm9trqN_iijBiq6UvFsCqxCFLELnyoQl3Y1H1t7RFRbB0DtgqF_cjwTKJt8CCopiANAA"},"schema":"pubphys.envelope/1"},"record_hash":"1c75c8063c36a7d6c08cdba885f650c4cc05bacbdb506ada402b318843a6fa7c","leaf_index":445}