{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"90814458d82691792dfdfb4c0df403916c28b1d3e05e54d39228e5b2a1689515","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9ca601b23f235f9328ff62248e67f75df58218e068f683bc00e3eca387269eb7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"amo.quantum-equivalence-principle.superposition-wep","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Since energy has mass, an atom in a quantum superposition of two energy levels has no single definite mass. Whether it still falls exactly like a normal atom is a question that classical physics cannot pose.","posed_since":"2015","precise":"In the quantum formulation of the equivalence principle (Zych and Brukner, arXiv 1502.00971), the internal mass-energy operator $M = m_0 + H_{\\mathrm{int}}/c^2$ may couple to gravity through operators $M_g$ and $M_i$ that differ off-diagonally. Bound the off-diagonal violation parameters for atoms prepared in coherent superpositions of hyperfine or optical clock states at better than $1e-12$, improving on the about $1e-9$ bound of Rosi et al 2017.","problem_ref":null,"references":"","settled_by":"An atom interferometer with test atoms in clock-state superpositions measuring the differential acceleration with sub-1e-12 precision.","status_note":"","title":"Do atoms in internal-energy superpositions obey the equivalence principle?","topic_ref":"1ef36fc0692a8bd1d924ba5b2faf894c475adb1314f3440a6281df6c8bcb9e1b"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"f9d5e291404e38224e1f97e59c4f73181555482ecbd088d175d956512c9c9ffc","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"f43f95d6234d564a893a9f697892111c4fb7d206f47f0dfab9e0e1f5f2a9f9c1","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"tUsYgqbvmNMS0IttS82JLDqKYsVOM84-3g-OTZ7F-EbVuKK1YLkfDoufDDcaVezgvVTi01jgtjJx4I8lcgjrCQ"},"schema":"pubphys.envelope/1"},"record_hash":"f9d5e291404e38224e1f97e59c4f73181555482ecbd088d175d956512c9c9ffc","leaf_index":451}