{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"e5e2186ccc2d6797836110eab7038cc2bda152a5a7eedf13cadb6ab91305a78a","created":"2026-10-03T07:17:59Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"44646c8e7329508ff4a7bfdaabff970d23a781f909c099ccbaeba77a5d618225","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"cm.flat-band-geometry.quantum-metric-measurement","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"The quantum metric measures how fast electron wavefunctions change across momentum space and is central to flat-band theories, but it has not been measured for the flat bands of moire graphene.","posed_since":"","precise":"Measure the Brillouin-zone-integrated quantum metric of the magic-angle graphene flat bands, for example through the optical sum rule that relates the frequency integral of $\\operatorname{Re}\\sigma_{xx}(\\omega)/\\omega$ for transitions out of a filled band to the integral of its quantum metric, or through polarization-resolved photoemission. An answer is the integrated tr g with uncertainty, compared with continuum-model predictions.","problem_ref":null,"references":"","settled_by":"Broadband infrared absorption sum-rule or polarization-resolved photoemission measurements on gated devices compared with continuum-model quantum metric.","status_note":"","title":"Direct measurement of the quantum metric of moire flat bands","topic_ref":"da008840aae42cdef1acabe867ba961afa7eeb44e1e073d87f5196b23679e171"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"d78d0db1f069e883537c12c445b1f6aa6809f6571cd0f4b362328b182c9c4ac2","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"8d6036f07707488d9bc906b380d45a8ec137683cab9b029b1872b6e221141879","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"IjtT-1GIEyio5UuJbIJNZfpc5LWm2zz1Tx43B4AfxwskM83diOvnPLi6DrgFQ9EftHXtqw5UQ4bs1_TlXIJ3CQ"},"schema":"pubphys.envelope/1"},"record_hash":"d78d0db1f069e883537c12c445b1f6aa6809f6571cd0f4b362328b182c9c4ac2","leaf_index":991}