{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"a7c34a1b5699af64a5b27a66e3ff61e82a0283e5dc88d28893af2ee4d128dfa3","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["47f385ae44134219db0d52874d8b6bd674e21dbcabb32767d26d030e087a5564","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"88a6ae105bc93124fe503b163af3f7d94a5ae1e7abf675f0344509e38a024087","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cm.excitonic-insulators.tmd-exciton-superfluid","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"In two semiconductor layers separated by a thin insulator, electrons in one layer and holes in the other bind into long-lived excitons and make the system insulating. Drag experiments show these excitons move as units, but frictionless superflow has not been shown.","posed_since":"","precise":"In $\\mathrm{MoSe_2}$/hBN/$\\mathrm{WSe_2}$ electron-hole double layers at equal densities $n_e = n_h$ of order $10^{11} \\text{ to } 10^{12}\\,\\mathrm{cm}^{-2}$, 2025 Coulomb-drag experiments found a drag ratio near 1 (perfect drag), showing transport by bound excitons. Determine whether the exciton fluid has a finite superfluid stiffness below a Berezinskii-Kosterlitz-Thouless temperature $T_{\\mathrm{BKT}}$, i.e. vanishing counterflow resistance or a Josephson-like interlayer response, and give $T_{\\mathrm{BKT}}$ versus density. An answer is yes or no with measured $T_{\\mathrm{BKT}}(n)$.","problem_ref":"47f385ae44134219db0d52874d8b6bd674e21dbcabb32767d26d030e087a5564","references":"","settled_by":"A counterflow transport measurement showing resistance vanishing below a density-dependent $T_{\\mathrm{BKT}}$, or a bound on stiffness excluding superfluidity down to the lowest accessible temperature.","status_note":"Two 2025 Science papers (Nguyen et al.; Qi et al.) reported perfect Coulomb drag, establishing exciton transport but not superfluidity.","title":"Is the $\\mathrm{MoSe_2}$/$\\mathrm{WSe_2}$ dipolar excitonic insulator an exciton superfluid?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"3ad7fc7315b5159f284796b37ce60c9cc71dd3292f6574099a2044f902c47d2b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"61cc7aea42bee8844539b5c8fc52e48ceb09402d8702032c3e85c5d5e6a0cf68","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"PvT7CbmWF07pXdzQrNJ4hdebK8QYRCxKUX8YTO7muDQYUIJ64dAvEh-Q16OL-veJwoV72BvCMRP2WVWbAVvMAA"},"schema":"pubphys.envelope/1"},"record_hash":"3ad7fc7315b5159f284796b37ce60c9cc71dd3292f6574099a2044f902c47d2b","leaf_index":2784}