{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b77fa0fedb96ef9a6ab303c70d659d1833f41c1963486f07bbdae67782a9159c","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["25c94828b16686eb5314eae282467cf6037f489af84a46eb4789f6c67b1cbcdc","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"d36584234bcd1b260ae86c1abfd776e119a8b6aaa45f8652d0841fa6683d3d93","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":["ai:gpt-5.5"],"external_id":"amo.dipolar-supersolids.superfluid-fraction-2d","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"In a supersolid only part of the matter flows freely (the superfluid fraction). It has been measured in a chain of droplets, but not in a two-dimensional crystal where it can depend on direction.","posed_since":"","precise":"For a 2D triangular or honeycomb supersolid of Dy-164 or Er-166, measure the superfluid fraction tensor $f_{s},ij$ (via Josephson oscillations, moment of inertia or sound speeds) as a function of density contrast, and compare with Leggett's upper and lower bounds computed from the measured density profile. Answer: $f_{s},ij$ versus contrast with errors.","problem_ref":"25c94828b16686eb5314eae282467cf6037f489af84a46eb4789f6c67b1cbcdc","references":"","settled_by":"A 2D measurement of $f_s$ along two lattice directions compared with Leggett bounds from in-situ imaging.","status_note":"A 2024 Josephson-effect measurement in a one-dimensional droplet array found a sub-unity fraction consistent with the Leggett bound (Biagioni et al., Nature 2024; arXiv:2311.04757).","title":"Superfluid fraction tensor of a two-dimensional dipolar supersolid","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"d5b65295ca33df6dcc766c5b0d78a5227356ba38e3738ee242cbe960a1077b86","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"3ac9c333a1b017a5dc5e06cf0ee1ab03d9d413bb830120a8b9463942d2fc5cb0","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"4Y9nkhmWSBC0UpJqXXq1ohM65I9l-1xw7mupn7BbK5g2zpl7cPD-NxBZx728CUTO0LL_3nPD8LXd9P7bMWb3BA"},"schema":"pubphys.envelope/1"},"record_hash":"d5b65295ca33df6dcc766c5b0d78a5227356ba38e3738ee242cbe960a1077b86","leaf_index":2216}