{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"52955221c595594c23c55060dd6cd44736dafd3cc1e96ef891a83750b6db1dfe","created":"2026-10-03T07:18:10Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","c2f73e932b001e465fd6cb1e0857d1ab82e7b70ced32116141d9edf9660d5b92"],"salt":"eb2657e3d9d24b6d7adb1f9660479a73bc175f0b2240fdc088446461877ecf2e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"qi.quantum-chemistry-algorithms.initial-state-overlap","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"c2f73e932b001e465fd6cb1e0857d1ab82e7b70ced32116141d9edf9660d5b92","relation":"special_case"}],"plain":"Quantum phase estimation needs a starting state that resembles the true ground state. If the best starting states that ordinary computers can prepare become exponentially worse as molecules grow, the quantum speedup disappears.","posed_since":"2022","precise":"For strongly correlated molecules and clusters (e.g. iron-sulfur clusters with $N_{\\mathrm{Fe}}$ iron atoms), determine how the maximal overlap $\\mid\\langle \\phi \\mid \\psi_0\\rangle\\mid^2$ between the ground state $\\psi_0$ and states $\\phi$ preparable classically in poly time (bounded-bond-dimension MPS, broken-symmetry determinants and short sums of them) scales with system size; exponential decay would remove the exponential advantage of phase estimation.","problem_ref":null,"references":"","settled_by":"Computed overlaps for a size series of a chemically relevant family large enough to fit the scaling, or a proof for a model family.","status_note":"","title":"Scaling of ground-state overlap for classically preparable trial states","topic_ref":"7a5b2e4d74deb25e82b2175151e253081cb18bcfd07a0463c8d69af524e27dcb"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"9e0a51780f4a850bccfe261421352606baff5f97aad216140223ecacd5ac5874","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"203dbdf5e39723dd5deeba97844b9afb238d28e6d349f1a821d2b3069171e36a","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"MbIlqYrkKJanjvbQS7t_tqgPmmdBOc5GqfeKf1glVJJmTtVG_LxN-CQA-XHP5Wj1wo5RJpStHTYhhfE4IEXtAg"},"schema":"pubphys.envelope/1"},"record_hash":"9e0a51780f4a850bccfe261421352606baff5f97aad216140223ecacd5ac5874","leaf_index":2029}